BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Probability

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 93
Joined: Tue Mar 18, 2008 9:28 am
Thanked: 2 times

Probability

by CITI29 » Thu Jul 10, 2008 11:27 am
In a certain animal population, for each of the first 3
months of life, the probability that an animal will die
during that month is 1/10 . For a group of 200 newborn
members of the population, approximately how many
would be expected to survive the first 3 months of
life?

(A) 140
(B) 146
(C) 152
(D) 162
(E) 170

ans : 'b'

explain pls
Top
Source: — Problem Solving |
GMAT Instructor
Posts: 26
Joined: Sun Jul 06, 2008 8:53 am
Location: New York City
Thanked: 1 times

by GMATDavid » Thu Jul 10, 2008 12:13 pm
Because the probability of death applies to each of the three months, you need to calculate how many are still alive at the end of each month.

At the end of the 1st month, it is expected that 20 will die (1/10 of 200), leaving only 180.

At the end of the 2d month, it is expected that 18 will die (1/10 of 180), leaving only 162.

At the end of the 3d month, it is expected that about 16 will die (1/10 of 162) leaving 146.
Top
Post new topic Post Reply
• Page 1 of 1