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

 It is currently 19 Aug 2018, 20:00

### 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

# The probability of picking a boy in a class is 1/3. If two boys are re

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Aug 2009
Posts: 6555
The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

25 Jan 2018, 21:12
00:00

Difficulty:

55% (hard)

Question Stats:

60% (00:45) correct 40% (01:15) wrong based on 67 sessions

### HideShow timer Statistics

The probability of picking a boy in a class is $$\frac{1}{3}$$. If two boys are removed from the class, the probability of picking a boy in the class goes down to $$\frac{5}{16}$$. What is the number of boys in the class?

(A) 20
(B) 22
(C) 32
(D) 34
(E) Data insufficient

New question
source - self

_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

Senior Manager
Joined: 29 Jun 2017
Posts: 493
GPA: 4
WE: Engineering (Transportation)
Re: The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

25 Jan 2018, 21:53
1
1
chetan2u wrote:
The probability of picking a boy in a class is $$\frac{1}{3}$$. If two boys are removed from the class, the probability of picking a boy in the class goes down to $$\frac{5}{16}$$. What is the number of boys in the class?

(A) 20
(B) 22
(C) 32
(D) 34
(E) Data insufficient

New question
source - self

let x be boys so total class 3x
now x-2 are boys so total are 3x-2
(x-2)/ (3x-2) = 5/16
16x-32 = 15x -10
16x-15x = 32-10
x=22

IMO B ??
_________________

Give Kudos for correct answer and/or if you like the solution.

Intern
Joined: 29 Jul 2017
Posts: 12
GMAT 1: 650 Q50 V27
Re: The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

26 Jan 2018, 04:27
Let the total number of students in the class be 'T' and,
the number of boys among them be 'B'.
Therefore, probability of picking a boy = B/T = 1/3 ...(1)
If two boys are removed from the class, the probability of picking a boy = (B-2)/(T-2) = 5/16 ...(2)
Solving the two equations we get B = 22

Ans B
Intern
Joined: 22 Aug 2017
Posts: 14
The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

26 Jan 2018, 07:10
1:3:4
(1+3= a total of 4)

5:16:21
(5+16= a total of 21)

With ratios, you can add the parts to get a whole (part:part:whole)

Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2759
Re: The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

29 Jan 2018, 11:00
chetan2u wrote:
The probability of picking a boy in a class is $$\frac{1}{3}$$. If two boys are removed from the class, the probability of picking a boy in the class goes down to $$\frac{5}{16}$$. What is the number of boys in the class?

(A) 20
(B) 22
(C) 32
(D) 34
(E) Data insufficient

The ratio of boys to total students is x : 3x, thus:

(x - 2)/(3x - 2) = 5/16

16(x - 2) = 5(3x - 2)

16x - 32 = 15x - 10

x = 22

_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

VP
Joined: 07 Dec 2014
Posts: 1069
The probability of picking a boy in a class is 1/3. If two boys are re  [#permalink]

### Show Tags

29 Jan 2018, 12:16
chetan2u wrote:
The probability of picking a boy in a class is $$\frac{1}{3}$$. If two boys are removed from the class, the probability of picking a boy in the class goes down to $$\frac{5}{16}$$. What is the number of boys in the class?

(A) 20
(B) 22
(C) 32
(D) 34
(E) Data insufficient

let b=boys in class
let 2b=girls in class
(b-2)/2b=5/11
b=22
B
The probability of picking a boy in a class is 1/3. If two boys are re &nbs [#permalink] 29 Jan 2018, 12:16
Display posts from previous: Sort by

# The probability of picking a boy in a class is 1/3. If two boys are re

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

# 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®.