Carcass wrote:
One person is to be selected at random from a group of 25 people. The probability that the selected person will be a male is 0.44, and the probability that the selected person will be a male who was born before 1960 is 0.28.
Quantity A |
Quantity B |
The number of males in the group who were born in 1960 or later |
4 |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Let M = number of males in the group (among 25 people)The probability that the selected person will be a male is 0.44So, we can write: M/
25 = 0.44
ASIDE: We can solve this equation for M in several ways. My approach is to rewrite 0.44 as a fraction
We get: M/
25 = 44/100
Simplify right side to get: M/
25 = 11/25
At this point, we can see that
M = 11In other words, there are
11 males in the group of 25 people
The probability that the selected person will be a male who was born before 1960 is 0.28Let B = number of people in the group who are BOTH male and born before 1960So, we can write: B/
25 = 0.28
We get: B/
25 = 28/100
Simplify right side to get: B/
25 = 7/25
At this point, we can see that
B = 7In other words, there are
7 people who are BOTH male
and born before 1960
RECAP: There are
11 males in the group of 25 people. Among those
11 males,
7 were born
BEFORE 1960
So, the other 4 males must have been born
AFTER 1960
So, we get:
Quantity A: 4
Quantity B: 4
Answer: C
Cheers,
Brent
_________________
Brent Hanneson - founder of Greenlight Test Prep