GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 25 Sep 2018, 14:22

### 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

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

# Math Revolution Approach (PS)

Author Message
Intern
Joined: 15 Oct 2014
Posts: 17
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

09 Feb 2017, 05:41
MathRevolution wrote:
If (n+2)!/n!=156, n=?
A. 2/131 B. 9 C. 10 D. 11 E. 12

==> From (n+2)!/n!=156 and (n+2)(n+1)n!/n!=(n+2)(n+1)=156=13*12, you get n+2=13, n=11.

Adding to this since it's a quadratic we will get 2 solutions 11,-14 but since -14 is not an option so n=11 is correct.

Sent from my iPhone using GMAT Club Forum mobile app
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

12 Feb 2017, 18:25
What is the difference between the circumferences of 2 circles such that the diameters of the circles are 10 and 11?

A. $$\frac{π}{2}$$
B. $$π$$
C. $$3\frac{π}{2}$$
D. $$2π$$
E. $$5\frac{π}{2}$$

==> The circumference of a circle is $$π$$d, thus $$π(11-10)= π$$.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 12 Feb 2017, 18:27 What is the number of multiples of 25 between $$5^4$$ and$$5^5$$, inclusive? A. 75 B. 96 C. 101 D. 121 E. 125 ==> The number of multiples become (last-first/n)+1, then you get $$\frac{5^5-5^4}{25}+1=\frac{(5-1)5^4}{25}+1=4(5^2)+1=101$$. 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

15 Feb 2017, 01:08
If 1 male, 2 females, and 1 child are to be randomly selected from 8 males, 10 females, and 8 children, how many such cases are possible?

A. 980
B. 1,440
C. 1,880
D. 2,480
E. 2,880

==> You get 8C1*10C2*8C1=(8)(45)(8)=2,880.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 18 Feb 2017, 08:04 What is the range of 30 consecutive even numbers? A. 54 B. 56 C. 58 D. 60 E. 62 ==> The number of consecutive numbers become (last-first/2)+1=(range/2)+1. In other words, from (range/2)+1=30, you get range/2=29, range=2(29)=58. 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

18 Feb 2017, 08:08
$$8^1^0-8^2$$ is the approximation of which of the following?

A. $$8^7$$
B. $$8^8$$
C. $$8^9$$
D. $$8^1^0$$
E. $$8^1^1$$

==> You get $$8^1^0-8^2=(8^8-1)8^2≒(8^8)(8^2)=8^1^0$$.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 19 Feb 2017, 18:45 When $$f(x)=x^2(1-x)^2$$, which of the following is equal to f(1-x)? A. f(x) B. f(x)/x C. f(-x2) D. f(x2) E. f(1) ==> You get $$f(1-x)=(1-x)^2(1-(1-x))^2=(1-x)^2x^2=f(x)$$. 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

19 Feb 2017, 18:47
Which of the following equivalent to $$(1/8)^4$$?

A. $$(0.5)^5$$
B. $$(0.25)^3$$
C. $$(0.25)^6$$
D. $$(0.4)^3$$
E. $$(0.8)^2$$

==> You get $$(1/8)^4=((1/2)^3)^4=(1/2)^1^2=((1/2)^2)^6=(1/4)^6=(0.25)^6$$.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 23 Feb 2017, 01:10 What is the difference between the hypotenuse’s length of the right triangle with 2 shorter sides of 10 and 24 and the hypotenuse’s length of the right triangle with 2 shorter sides of 7 and 24? A. 1 B. 2 C. 3 D. 4 E. 5 ==>For Pythagorean Theorem, 5:12:13=10:24:26 and 7:24:25 appear most frequently. Thus, the length of hypotenuse each becomes 26 and 25, and the difference becomes 26-25=1. 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

24 Feb 2017, 02:14
10+8÷3×6-2=?

A. 24
B. 34
C. 22
D. 12
E. 11

==> When calculating the numbers, even if there are no brackets, multiplication and division come first.
You get 10+8÷3×6-2=10+(8/3)6-2=10+16-2=24.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Manager Joined: 21 Feb 2017 Posts: 77 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 25 Feb 2017, 23:20 MathRevolution wrote: In the x- y plane, there are 4 points (0,0), (0,4), (6,4), and (6,0). If these 4 points makes a rectangle, what is the probability that x+y<4? A. 1/2 B. 1/3 C. 1/4 D. 1/5 E. 2/5 ANS: As you can see from the diagram below, the correct answer is 1/3. Hence, B is our answer choice. Please describe how 1/3 is correct? Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 26 Feb 2017, 21:30 Attachment: 1.png [ 2.59 KiB | Viewed 443 times ] There is a circle inscribed in a square, shown on the above figure. If the length of the square is 2, what is the area of one of the 4 regions shaded? A. $$1-π$$ B. $$2-π$$ C. $$4-π$$ D. $$1-(\frac{π}{2})$$ E. $$1-(\frac{π}{4})$$ ==> The area of the square-area of the $$circle=2^2- π=4- π$$, and since it asks for one of the 4 regions shaded, you get $$\frac{4- π}{4}=1-(\frac{π}{4})$$. 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

26 Feb 2017, 21:34
What is the scope including 1/11+1/12+1/13+......+1/20?

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

==>The sum of consecutive reciprocal number sequence is decided by the first number and the last number. Thus, from
10/20=1/11+1/12+.....+1/20<1/11+1/12+.....+1/20<1/11+1/12+.....+1/20=10/11, you get 1/2=10/20<1/11+1/12+.....+1/20<10/11<1, which becomes 1/2~1.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Math Revolution Approach (PS) [#permalink] ### Show Tags Updated on: 26 Feb 2017, 22:23 MathRevolution wrote: In the x- y plane, there are 4 points (0,0), (0,4), (6,4), and (6,0). If these 4 points makes a rectangle, what is the probability that x+y<4? A. 1/2 B. 1/3 C. 1/4 D. 1/5 E. 2/5 ANS: As you can see from the diagram below, the correct answer is 1/3. Hence, B is our answer choice. Attachments 1.png [ 10.85 KiB | Viewed 424 times ] _________________ 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Originally posted by MathRevolution on 26 Feb 2017, 21:50.
Last edited by MathRevolution on 26 Feb 2017, 22:23, edited 2 times in total.
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82

### Show Tags

26 Feb 2017, 21:55
As you can see from the diagram above, the area of the red rectangle is 24 and the area of the triangle below green line is 8.
The ratio of the area of the triangle to that of the red rectangle is 1/3.
Hence, B is our answer choice.
_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Math Revolution Approach (PS) [#permalink] ### Show Tags 26 Feb 2017, 22:14 awdxzs wrote: MathRevolution wrote: If (n+2)!/n!=156, n=? A. 2/131 B. 9 C. 10 D. 11 E. 12 ==> From (n+2)!/n!=156 and (n+2)(n+1)n!/n!=(n+2)(n+1)=156=13*12, you get n+2=13, n=11. Therefore, the answer is D Adding to this since it's a quadratic we will get 2 solutions 11,-14 but since -14 is not an option so n=11 is correct. Sent from my iPhone using GMAT Club Forum mobile app Hello, goalMBA1990 The area of the red rectangle is 24 and the area of the triangle below green line is 8. The ratio of the area of the triangle to that of the red rectangle is 1/3. _________________ 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

26 Feb 2017, 22:22
As you can see from the diagram above, the area of the red rectangle is 24 and the area of the triangle below the green line is 8.
The ratio of the triangle area to the red rectangle area is 8/24 or 1/3.
Hence, B is our answer choice.
_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 26 Feb 2017, 22:25 As you can see from the diagram below, the area of the red rectangle is 24 and the area of the triangle below green line is 8. The ratio of the area of the triangle to that of the red rectangle is 1/3. Hence, B is our answer choice. Attachments 1.png [ 10.85 KiB | Viewed 424 times ] _________________ 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 6242
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

01 Mar 2017, 04:50
40,105*26*10,112 is the approximation of which of the following?

A. $$10^8$$
B. $$10^9$$
C. $$10^1^0$$
D. $$10^1^1$$
E. $$10^1^2$$

==> You get $$40,105*26*10,112≒40,000*25*10,000=100*10^4*10^4=10^2*10^4*10^4=10^2^+^4^+^4=10^1^0$$.

_________________

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.
"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6242 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 02 Mar 2017, 01:39 The standard deviation of which of the following is equivalent with that of $${m, r, p, n}$$? A. {$${2m, 2r, 2p, 2n}$$} B. {$${m+2, r+2, p+2, n+2}$$} C. {$${|m|, |r|, |p|, |n|}$$} D. {$${\frac{1}{m}, \frac{1}{r}, \frac{1}{p}, \frac{1}{n}}$$} E. {$${m^2, r^2, p^2, n^2}$$} ==> For standard deviation, if the elements move in parallel, they have the same standard deviation. Thus, the standard deviation of {m, r, p, n} is equal to the standard deviation of {m+2, r+2, p+2, n+2}. Therefore, 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. "Only$99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Re: Math Revolution Approach (PS) &nbs [#permalink] 02 Mar 2017, 01:39

Go to page   Previous    1  ...  5   6   7   8   9   10   11  ...  28    Next  [ 553 posts ]

Display posts from previous: Sort by

# Math Revolution Approach (PS)

Moderator: souvonik2k

## Events & Promotions

 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®.