probability

Expert replies

bacali: Master | Next Rank: 500 Posts; Posts: 245; Joined: Thu Aug 16, 2007 12:41 pm

by bacali » Tue Dec 02, 2008 9:56 am

Six cards numbered from 1 to 6 are placed in an empty bowl. First one card is drawn and then put back into the bowl; then a second card is drawn. If the cards are drawn at random and if the sum of the numbers on the cards is 8, what is the probability that one of the two cards drawn is
numbered 5 ?

A 1/6
B 1/5
C 1/3
D 2/5
E 2/3

OA: D

Like this post

Source: Beat The GMAT — Problem Solving | Tue Dec 02, 2008 9:56 am

hwiya320: Senior | Next Rank: 100 Posts; Posts: 93; Joined: Tue Sep 02, 2008 5:34 pm; Thanked: 7 times

Re: probability

by hwiya320 » Tue Dec 02, 2008 10:13 am

bacali wrote:Six cards numbered from 1 to 6 are placed in an empty bowl. First one card is drawn and then put back into the bowl; then a second card is drawn. If the cards are drawn at random and if the sum of the numbers on the cards is 8, what is the probability that one of the two cards drawn is
numbered 5 ?

D 2/5

correct me if I'm wrong.

It first states sum of two cards is 8
Possible outcome - card that will add upto 8 within 1-6 =
2,6
3,5
4,4
5,3
6,2
so 5 possible outcome. 5 only shows once, so you have 1/5 chance to pick 5 in the first draw.
Same for second draw, so 1/5 + 1/5 = 2/5

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review