Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

 It is currently 16 Jul 2019, 09:44

### 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

# Math Revolution Approach (PS)

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

05 Apr 2017, 01:22
If (4/9)÷n=3/5, n=?

A. 20/27
B. 27/20
C. 10/9
D. 9/10
E. 9/4

==>(4/9)÷n=3/5 -> (4/9)(1/n)=3/5. And 4/9n=3/5 -> n=(4/9)(5/3)=20/27.

Hence, 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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 06 Apr 2017, 01:02 $$\frac{2^{x-1}}{2^{1-x}}$$ is equal to which of the following? A. $$4^{x-1}$$ B. $$4^{1-x}$$ C. $$4^{2x}$$ D. $$4^{-2x}$$ E. $$4^x$$ ==> You get $$\frac{2^{x-1}}{2^{1-x}} =2^{x-1-(1-x)}=2^{2(x-1)}=4^{x-1}$$. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

07 Apr 2017, 02:02
It’s well known that a company's profit=10,000x-50x^2, where x is the number of workers. If the profit of the company is the greatest, what is the value of x?

A. 5
B. 10
C. 50
D. 80
E. 100

==> From $$y=f(x)=ax^2+bx+c$$, if $$x=\frac{-b}{2a}$$, f(x) becomes either maximum or minimum. Thus, profit=$$-50x^2+10,000x$$, and in order for the profit to become the greatest, you get $$x=\frac{-10,000}{2(-50)}=100$$.

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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 09 Apr 2017, 18:37 What is the range of 25 consecutive even numbers? A. 44 B. 46 C. 48 D. 50 E. 52 ==> The number of consecutive even numbers=(The last number-the first number)/2 +1=range/2+1, so from range/2+1=25, range/2=25-1=24, you get range=2(24)=48. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

09 Apr 2017, 18:38
If 1 male, 2 females, and 1 child are to be selected at random from 8 males, 10 females, and 8 children, respectively, how many such cases are possible?

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

==> From (8C1)(10C2)(8C1)=(8)(10*9/2!)(8)=2,880, 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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 12 Apr 2017, 01:14 When $$5^{11}$$ and $$2^n7^2$$ have the same number of factors, what is the value of n? A. 2 B. 3 C. 4 D. 5 E. 6 ==> From 11+1=(n+1)(2+1), you get 12=3(n+1), and n-3. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

13 Apr 2017, 18:16
If $$x^{-2}+x^{-1}=0$$, $$x=$$?

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

==> If you multiply x^2 on both sides, you get 1+x=0, x=-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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 14 Apr 2017, 07:37 Attachment: a.png [ 1.09 KiB | Viewed 606 times ] If the distances between two consecutive points are the same, what is the value of A in terms of x and y? A. 3y-2x B. 3x-2y C. 2x-3y D. 2y-3x E. 3y+2x ==> The distance between 2 consecutive points=d, hence d=y-x and A=y+2d=y+2(y-x)=3y-2x. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

16 Apr 2017, 18:29
If 3 juniors from 8 juniors are selected at random to make a committee, how many cases are possible?

A. 8
B. 28
C. 35
D. 42
E. 56

==> In general, you solve probability questions using nCr, a combination. In other words, from 8C3=56, 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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 16 Apr 2017, 18:30 If xy>0, which of the following must be positive? A. $$x$$ B. $$y$$ C. $$x^2y$$ D. $$y^2x$$ E. $$x^3y$$ ==> Squares are always positive, so the inequality sign doesn’t change even if you multiply or divide. Thus, from xy>0 and $$(x^2)xy>(x^2)0$$, you get $$x^3y>0$$. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

19 Apr 2017, 01:37
If $$a>b>0$$, $$a^2+b^2=6ab$$, $$\frac{(a+b)}{(a-b)}=$$?

A. 1

B. $$\sqrt{2}$$

C. $$\sqrt{3}$$

D. $$\sqrt{5}$$

E. 2

==> From $$(a+b)^2=a^2+b^2+2ab=6ab+2ab=8ab$$, you get $$a+b=\sqrt{8ab}$$
And from $$(a-b)^2=a^2+b^2-2ab=6ab-2ab=4ab$$, you get $$a-b=\sqrt{4ab}$$ and
$$\frac{(a+b)}{(a-b)}=\sqrt{8ab}/\sqrt{4ab}=2$$.

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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 20 Apr 2017, 01:43 Attachment: a.png [ 3.61 KiB | Viewed 579 times ] Attachment: b.png [ 2.23 KiB | Viewed 579 times ] From the above, you get $$h:(s-r)/2=√3:1$$ and $$h=√3(s-r)/2$$. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

21 Apr 2017, 01:29
1-0.000001=?

A. 1.001*0.999
B. 1.0001*0.9999
C. 1.001*0.9999
D. 1.0001*0.999
E. 1.01*0.99

==> You get $$a^2-b^2=(a+b)(a-b)$$, and thus $$1-0.000001=1^2-0.001^2=(1+0.001)(1-0.001)=1.001*0.999$$.

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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 24 Apr 2017, 02:49 When a certain coin is flipped, the probability that the coin will land on head or tail is 1/2 each. If the coin is flipped 4 times, what is the probability that it will land on tail at least twice on 4 flips? A. $$\frac{3}{8}$$ B. $$\frac{1}{16}$$ C. $$\frac{1}{2}$$ D. $$\frac{5}{8}$$ E. $$\frac{11}{16}$$ ==> In general, you solve probability questions using nCr combination. In other words, from TTHH, there are (4!/2!/2!)=6 possibilities, so you get (1/2)(1/2)(1/2)(1/2)*6=3/8. From TTTH, there are (4!/3!)=4 possibilities, so you get (1/2)(1/2)(1/2)(1/2)*4=1/4. From TTTT, there is only 1 possibility, so you get (1/2)(1/2)(1/2)(1/2)=1/16 and (3/8)+(1/4)+(1/16)=(6+4+1)/16=11/16. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

24 Apr 2017, 02:50
Which of the following is equal to $$\frac{(n+2)!}{n!}$$?

A. $$n(n+1)$$
B. $$1+(\frac{2}{n})$$
C. $$n^2+3n+2$$
D. $$n^2+2n$$
E. $$n+2$$

==> Since (n+2)!=(n+2)(n+1)n!, from (n+2)!/n!=(n+2)(n+1)n!/n!=(n+2)(n+1)
=$$n^2+3n+2$$, 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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 26 Apr 2017, 01:17 When a/b=1.2, (a-b)/(a+b)=? A. $$\frac{1}{15}$$ B. $$\frac{1}{11}$$ C. $$\frac{1}{9}$$ D. $$\frac{3}{8}$$ E. $$\frac{1}{3}$$ ==> From a/b=1.2=6/5, if you substitute a=6 and b=5, you get (a-b)/(a+b)=(6-5)/(6+5)=1/11. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

27 Apr 2017, 01:51
If two times x is 5 greater than three times y, what is the value of y, in terms of x?

A. y=2x-5
B. y=6x-5
C. y=(x/2)-5
D. y=(x/3)-5
E. y=(2x-5)/3

==> According to the ivy approach, is:”=”, greater than:”+”, hence you get 2x=5+3y. Thus, from 3y=5-2x, y=(2x-5)/3, 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 $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 28 Apr 2017, 01:35 If the sum of the annual salary of n persons is$x and the monthly salary per person is $y, what is the value of n in terms of x and y? A. $$\frac{x}{12y}$$ B. $$\frac{12x}{y}$$ C. $$12xy$$ D. $$\frac{12y}{x}$$ E. $$\frac{xy}{12}$$ ==> If the annual salary per person: s, you get ns=x, s=12y. If you substitue this, you get n(12y)=x, $$n=\frac{x}{12y}$$. 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$79 for 1 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: 7588
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: Math Revolution Approach (PS)  [#permalink]

### Show Tags

30 Apr 2017, 18:12
$$(5+\frac{1}{5})^2-(5-\frac{1}{5})^2$$=?

A. 2
B. 3
C. 4
D. 5
E. 9

==> Since $$a^2-b^2=(a-b)(a+b)$$, you get $$(5+\frac{1}{5})^2-(5-\frac{1}{5})^2=[(5+\frac{1}{5})-(5-\frac{1}{5})][(5+\frac{1}{5})+(5-\frac{1}{5})]=(\frac{2}{5})(10)=4$$.

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 $79 for 1 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: 7588 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: Math Revolution Approach (PS) [#permalink] ### Show Tags 30 Apr 2017, 18:13 If n is the product of 3 consecutive integers, which of the following must be true? I. a multiple of 2 II. a multiple of 3 III. a multiple of 4 A. I only B. II only C. III only D. I and II only E. II and III only ==> From n=m(m+1)(m+2) , where m=integer, the product of 3 consecutive integers is always a multiple of 6. Thus, I and II is always true. For III, if m=1, from n=(1)(2)(3)=6, it is not a multiple of 4, hence it is false. 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. "Only$79 for 1 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)   [#permalink] 30 Apr 2017, 18:13

Go to page   Previous    1  ...  7   8   9   10   11   12   13  ...  29    Next  [ 568 posts ]

Display posts from previous: Sort by

# Math Revolution Approach (PS)

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

Moderator: souvonik2k

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