It is currently 13 Dec 2017, 09:13

Decision(s) Day!:

CHAT Rooms | Ross R1 | Kellogg R1 | Darden R1 | Tepper R1


Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Math Revolution Approach (PS)

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 25 Oct 2017, 01:20
[GMAT math practice question]

The number of club X’s members is increased by 20 percent every year. If the number of members of the club X in 2000 was m, how many number of members in 2005 are greater than that of members in 2004?

A. (0.2)(1.2)^4m
B. (0.8)(1.2)^4m
C. (0.2)(1.2)^5m
D. (0.8)(1.2)^5m
E. (0.8)^4(1.2)^4m

=>

(1.2)^5m – (1.2)^4m = (1.2)^4m(1.2-1) = (0.2)(1.2)^4m

Therefore, the answer is A.

Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 25 Oct 2017, 23:47
[GMAT math practice question]

There are 3 machines with the same work rate. If it took t hours for 3 machines to work and took t+2 hours for 2 machines when working together, what is the value of k?

A. 4
B. 5
C. 6
D. 7
E. 9


=>

Assume X is the time one machine takes to work.

1/T=3/X and 1/T+2=2/X

X = 3T and X = 2(T+2).
We have 3T = 2T + 4 or T = 4.

Thus, the answer is A.

Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 27 Oct 2017, 00:31
[GMAT math practice question]

Let function f(x)=(x-a)(x-b). If f(10)=f(20)=0, f(30)=?

A. 50
B. 100
C. 150
D. 200
E. 250

=>

Since f(10) = f(20) = 0, f(x) = (x-10)(x-20).
f(30) = (30-10)(30-20) = 20*10 = 200.
Therefore, the answer is D.

Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 29 Oct 2017, 17:05
[GMAT math practice question]

(1/26)+(1/27)+……+(1/49)+(1/50) is included in which of the following ranges?

A. (1/6)~(1/5)
B. (1/5)~91/4)
C. (1/4)~(1/3)
D. (1/3)~(1/2)
E. (1/2)~1

=>

1/26 > 1/50, 1/27 > 1/50, …, 1/49 > 1/50
(1/26)+(1/27)+……+(1/49)+(1/50) > 1/50 + 1/50 + … + 1/50 = (1/50)*25 = 1/2.
1/26 < 1/25, 1/27 < 1/25, … , 1/49 < 1/25, 1/50 < 1/25.
(1/26)+(1/27)+……+(1/49)+(1/50) < 1/25 + 1/25 + … + 1/25 = (1/25)*25 = 1.

Therefore, the answer is E.
Answer : E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 29 Oct 2017, 17:07
[GMAT math practice question]

Tom traveled the entire 90 km trip. If he travelled the first 18 km of the trip at a constant rate of 36 km per hour and the remaining trip at a constant rate of 72 km per hour, what is his average speed?

A. 30 km/h
B. 36 km/h
C. 45 km/h
D. 48 km/h
E. 60 km/h

=>

90 / (18/36 + 72/72) = 90 / 1.5 = 60

Therefore, the answer is E.
Answer: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 01 Nov 2017, 00:58
[GMAT math practice question]

If f(x+y) = f(x)f(y), which of followings can be the value of f(0)?

I. 0
II. 1
III. 2

A. I only
B. II only
C. III only
D. I and II only
E. I, II and III



=>

When we plug in x = 0 and y = 0, we have f(0) = f(0)f(0) or f(0)f(0) – f(0) = 0.
Then f(0){ f(0) – 1 } = 0, so we have f(0) = 0 or f(0) = 1.

Therefore, D is the answer.

Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Intern
Intern
avatar
B
Joined: 01 Jan 2016
Posts: 2

Kudos [?]: 1 [0], given: 5

Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 01 Nov 2017, 02:09
MathRevolution wrote:
A larger cube has 27 cubic inch as a volume and in the cube there are 27 smaller cubes such that their volume is 1 cubic inch. What is the difference between the surface areas’ sum of the 27 smaller cubes and the surface area of the larger cube, in square inch?
A. 54
B. 64
C. 81
D. 108
E. 120

ANS: If we calculate 6*27-6*9=108, D becomes our answer.

Can you explain this one ?

Kudos [?]: 1 [0], given: 5

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 02 Nov 2017, 00:11
[GMAT math practice question]

If x=-1 and n is the sum of all prime numbers less than 100, what is the value of x^n+x^{n+1}+x^{n+2}+x^{n+3}+x^{n+4}+x^{n+5}?

A. -2
B. -1
C. 0
D. 1
E. 2

=>

Whatever the value of n is, (-1)^n+(-1)^{n+1}+(-1)^{n+2}+(-1)^{n+3}+(-1)^{n+4}+(-1)^{n+5} = 0, since two consecutive integer n and n+1 always have an odd integer and an even integer, and so (-1)^n+(-1)^{n+1} = 0.

Thus, the answer is C.

Answer: C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 02 Nov 2017, 09:22
bhateja wrote:
MathRevolution wrote:
A larger cube has 27 cubic inch as a volume and in the cube there are 27 smaller cubes such that their volume is 1 cubic inch. What is the difference between the surface areas’ sum of the 27 smaller cubes and the surface area of the larger cube, in square inch?
A. 54
B. 64
C. 81
D. 108
E. 120

ANS: If we calculate 6*27-6*9=108, D becomes our answer.

Can you explain this one ?



The edge of the larger cube is 3 and the area of one face is 9.
And the cube has 6 faces.

The edge of the smaller cube is 1 and each face has the area 1.

6*27 means the sum of 6 faces area of the smaller cube times 27 cubes.
6*9 is the number of faces 6 times the area of each face 9.

6*27 - 6*9 is the answer.

Happy Studying !!!
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 04 Nov 2017, 17:20
[GMAT math practice question]

When x/y = 1.2, (x^2-y^2)/(x^2+y^2) =?

A. 10/51
B. 11/51
C. 10/61
D. 11/61
E. 11/71

=>

x/y = 6/5.
(x^2-y^2)/(x^2+y^2) = ((x/y)^2-1)/((x/y)^2+1) = ((6/5)^2 – 1 ) / ((6/5)^2 + 1 )
= (6^2-5^2)/(6^2+5^2) = (36-25)/(36+25) = 11/61

Therefore, the answer is D.

Answer: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 05 Nov 2017, 17:25
[GMAT math practice question]

(3^3+3^4+3^5+3^6)^2=?

A. 2^43^65^2
B. 2^63^45^2
C. 2^83^65^2
D. 2^63^85^2
E. 2^63^65^2

=>
(3^3+3^4+3^5+3^6)^2= (3^3(3^0+3^1+3^2+3^3))^2=3^6(1+3+9+27)^2=3^640^2=3^62^65^2

Therefore, the answer is E.
Answer: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 05 Nov 2017, 17:27
[GMAT math practice question]

Which of the following equations has a unique integer solution?

A. y=3x
B. y=(x/3)+4
C. y=√2x
D. y=(1/2)x
E. y=(-1/x)+2


=>

A. x = 0, y = 0 / x = 1, y = 3
B. x = 0, y = 4 / x = 3, y = 5
C. y=√2x has a unique integer solution, that is, x = 0 and y = 0. If x is not 0, y is an irrational number, which is not an integer.
D. x = 0, y = 0 / x = 2, y = 1
E. x = 1, y = 1 / x = -1, y = 3

Therefore, the answer is C.
Answer : C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 08 Nov 2017, 23:57
[GMAT math practice question]

What of the followings is the range of X = 1 + (1/2^2) + (1/3^2) + ...... + (1/100^2),

A. 0 < X < 1
B. 1 < X < 2
C. 2 < X < 3
D. 3 < X < 4
E. 4 < X < 5

=>

1/A^2 < 1/{(A-1}A} = 1/(A-1) – 1/A

It is clear that 1 + (1/2^2) + (1/3^2) + ...... + (1/100^2) > 1.

1 + (1/2^2) + (1/3^2) + ...... + (1/100^2)
< 1 + 1/(1∙2) + 1/(2∙3) +1/(3∙4) + … + 1/(99∙100)
= 1 + ( 1/1 – 1/2 ) + ( 1/2 – 1/3 ) + … + (1/99 – 1/100)
= 1 + 1/1 – 1/100 = 2 – 1/100 < 2

Thus 1 < X < 2.
Therefore, B is the answer.

Answer: B
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 09 Nov 2017, 00:00
[GMAT math practice question]

The probability that an event A occurs is 1/2 and the probability that an even B occurs is 1/3. If event A and event B are independent, what is the probability that event A occurs but event B does not occur?

A. 1/6
B. 1/3
C. 1/2
D. 2/3
E. 5/6


=>

Since events A and B are independent, P(A∩B) = P(A) ∙P(B).
The probability P(A-B) = P(A) - P(A∩B) = P(A) - P(A) ∙P(B) = 1/2 – (1/2)(1/3) = 1/2 – 1/6 = 2/6 = 1/3.

Thus, the answer is B.
Answer: B
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 12 Nov 2017, 18:03
[GMAT math practice question]

What is the sum of the remainders when the first 50 positive integers are divided by 5?

A. 60
B. 70
C. 80
D. 90
E. 100

=>

1, 2, 3, 4, 5 have remainders 1, 2, 3, 4, 0 and the sum of their remainders is 1 + 2 + 3 + 4 + 0 = 10.
6, 7, 8, 9, 10 have remainders 1, 2, 3, 4, 0 and the sum of their remainders is 1 + 2 + 3 + 4 + 0 = 10.

46, 47, 48, 49, 50 have remainders 1, 2, 3, 4, 0 and the sum of their remainders is 1 + 2 + 3 + 4 + 0 = 10.

10 * 10 = 100

Therefore, the answer is E.

Answer: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 12 Nov 2017, 18:04
[GMAT math practice question]

In a pin factory, it needs to produce 100,000 pins every day, and 5 machines take x hours to produce 100,000 pins. One day, one of the machines is out of order, so only 4 machines worked. These four machines took x+2 hours to produce 100,000 pins, and each machine’s work rates are the same. What is the value of x?

A. 5
B. 6
C. 7
D. 8
E. 9

=>

Assume T is the time that one machine takes to produce 100,000 pins.

1/x = 5/T and 1/(x+2) = 4/T
5x = T and T = 4(x+2)
5x = 4(x+2)
5x = 4x + 8
x = 8.

Therefore, the answer is D.
Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 15 Nov 2017, 00:52
[GMAT math practice question]

In the normal x-y coordinate plane there are 4 points A(-1,3), B(3,3), C(-1,7), and D(3,7). If a line passing through the origin bisects the area of the rectangle ABCD, what is the slope of the line?

A.5
B. 6
C. 7
D. 8
E. 9

=>

The line should pass through the center of the rectangle ABCD.
Then the center is ((-1+3)/2, (3+7)/2) or (1,5)
The slope of the line passing though (0,0) and (1,5) is 5-0/1-0=5.

Therefore, the answer is A.
Answer : A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 16 Nov 2017, 00:42
[GMAT math practice question]

I. 1/2,2/3,3/4,4/5,5/6
II. 1/2,1/3,1/4,1/5,1/6
III. 1/6,2/6,3/6,4/6,5/6

For which of the above lists is the average of the numbers less than the median of numbers?

A. I only
B. II only
C. III only
D. II and III
E. I, II and III




=>
I. The differences between the consecutive terms are 1/6 (= 2/3 – 1/2 ), 1/12 (= 3/4 – 2/3 ), 1/20 (= 4/5 – 3/4 ), and 1/30 (= 5/6 – 4/5). As these are decreasing, the average is smaller than the median.

II. The differences between consecutive terms are - 1/6(= 1/3 – 1/2),-1/12(= 1/4 – 1/3 ), - 1/20(= 1/5 – 1/4), and -1/30(= 1/6 – 1/5). As these are increasing, the average is larger than the median.

III. As the data are symmetric, the average and the median are equal.

Therefore, the answer is A

Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 17 Nov 2017, 00:23
[GMAT math practice question]

Which of the following is true if -3<x<9?

A. |x-3|<4
B. |x-3|<5
C. |x-3|<6
D. |x-3|>4
E. |x-3|>5

=>

|x-a|<b
⟺ -b < x – a < b
⟺ a - b < x < a + b
So, a is the midpoint of the end points a – b and a + b, and
b is half the distance between the end points a – b and a + b.

The midpoint of -3 and 9 is [(-3)+9]/2 = 6/2 = 3. So, a = 3.
Since the distance between -3 and 9 is 12, b = 12/2= 6.
Thus, |x-3| < 6.

Therefore, the answer is C.

Answer: C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4467

Kudos [?]: 3145 [0], given: 0

GPA: 3.82
Premium Member
Re: Math Revolution Approach (PS) [#permalink]

Show Tags

New post 19 Nov 2017, 17:23
[GMAT math practice question]

In how many ways can three boys and four girls line up in a row, if girls take the first and last positions?

A. 28
B. 120
C. 720
D. 1,440
E. 5,040

=>

There are four ways (girls) to fill the first position and three ways (girls left over) to fill the last position. The remaining five positions can be filled by the five remaining children (three boys and two girls) in 5!=120 ways.

By the multiplication rule, there are 4 * 3 * 120 = 1,440 different lines possible.

Therefore, the answer is D.

Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 3145 [0], given: 0

Re: Math Revolution Approach (PS)   [#permalink] 19 Nov 2017, 17:23

Go to page   Previous    1  ...  7   8   9   10   11   12   13   14   15   16   17   18    Next  [ 358 posts ] 

Display posts from previous: Sort by

Math Revolution Approach (PS)

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.