A bag contains x blue chips and y red chips. If the probability

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BTGModeratorVI: Legendary Member; Posts: 1223; Joined: Sat Feb 15, 2020 2:23 pmFollowed by: 1 member

by BTGModeratorVI » Tue Feb 18, 2020 11:07 am

A bag contains x blue chips and y red chips. If the probability of selecting a red chip at random is 3/7, then x/y =

A. 7/11
B. 3/4
C. 7/4
D. 4/3
E. 11/7

Answer: D
Source: Magoosh

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Source: Beat The GMAT — Problem Solving | Tue Feb 18, 2020 11:07 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

Re: A bag contains x blue chips and y red chips. If the probability

by Brent@GMATPrepNow » Wed Feb 19, 2020 6:38 am

BTGModeratorVI wrote: ↑
Tue Feb 18, 2020 11:07 am
A bag contains x blue chips and y red chips. If the probability of selecting a red chip at random is 3/7, then x/y =

A. 7/11
B. 3/4
C. 7/4
D. 4/3
E. 11/7

Answer: D
Source: Magoosh

We can quickly solve this question by testing values that satisfy the given information

GIVEN: The probability of selecting a red chip at random is 3/7
So, it COULD be the case that there are 3 red chips, and a TOTAL of 7 chips
If there are 7 chips and 3 are red, then the other 4 chips must be blue
In other words, y = 3 and x = 4

This means x/y = 4/3

Answer: D

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8177; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

Re: A bag contains x blue chips and y red chips. If the probability

by Scott@TargetTestPrep » Mon Mar 09, 2020 4:07 am

BTGModeratorVI wrote: ↑
Tue Feb 18, 2020 11:07 am
A bag contains x blue chips and y red chips. If the probability of selecting a red chip at random is 3/7, then x/y =

A. 7/11
B. 3/4
C. 7/4
D. 4/3
E. 11/7

Answer: D
Source: Magoosh

Based on the given information, we can create the equation:

y/(x + y) = 3/7

3(x + y) = 7y

3x + 3y = 7y

3x = 4y

x/y = 4/3

Answer: D

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