What is the probability of selecting a number divisible by..

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AAPL: Moderator; Posts: 2599; Joined: Sun Oct 29, 2017 2:08 pm; Followed by:2 members

What is the probability of selecting a number divisible by..

by AAPL » Sun Dec 03, 2017 12:21 pm

What is the probability of selecting a number divisible by three from a set of five consecutive even numbers?

A. 2/3
B. 1/2
C. 1/4
D. 1/5
E. It cannot be determined from the information given.

The OA is E.

Why that is the correct question?

For example, if I take the numbers 2, 4, 6, 8, 10, in this case the probability of selecting a number divisible by 3 is, 1/5, right?

Experts, can you assist me with this PS question, please?

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Source: Beat The GMAT — Problem Solving | Sun Dec 03, 2017 12:21 pm

GMAT/MBA Expert

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

by Brent@GMATPrepNow » Sun Dec 03, 2017 2:49 pm

AAPL wrote:What is the probability of selecting a number divisible by three from a set of five consecutive even numbers?

A. 2/3
B. 1/2
C. 1/4
D. 1/5
E. It cannot be determined from the information given.

The OA is E.

Why that is the correct question?

For example, if I take the numbers 2, 4, 6, 8, 10, in this case the probability of selecting a number divisible by 3 is, 1/5, right?

Experts, can you assist me with this PS question, please?

You are correct.
IF the 5 even numbers are {2, 4, 6, 8, 10} then 6 is the only number that's divisible by 3.
So, P(select even) = 1/5

However, if the 5 even numbers are {6, 8, 10, 12, 14} then 6 and 12 are both divisible by 3.
So, P(select even) = 2/5

Answer: E

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Sat Oct 12, 2019 3:53 pm

AAPL wrote:What is the probability of selecting a number divisible by three from a set of five consecutive even numbers?

A. 2/3
B. 1/2
C. 1/4
D. 1/5
E. It cannot be determined from the information given.

If the 5 consecutive even numbers are 2, 4, 6, 8, and 10, then the probability of selecting a multiple of 3 is 1/5. However, if the numbers are 6, 8, 10, 12, and 14, then the probability is 2/5. Therefore, it cannot be determined from the information given.

Answer: E

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