nades09
In a 200 member association consisting of men and women, exactly 20% of men and exactly 25 % women are homeowners. What is the least number of members who are homeowners?
A. 49
B. 47
C. 45
D. 43
E. 41
There are many ways to solve this question. One of the most efficient would be to use integer solutions method since number of men and women have to be integers.
Method 1: To minimize the number of homeowners, we must make the number of men as large as possible since only 20% of those are homeowners. Of the rest, 25% will be homeowners.
Since 20% of men are homeowners, it means the total number of men is a multiple of 5 (because 1/5 of men are homeowners which must be an integer). So say number of men = 5a
Since 25% of women are homeowners, it means the total number of women is a multiple of 4 (because 1/4 of women are homeowners which must be an integer). So say number of women = 4b
5a + 4b = 200
To minimize the number of homeowners, we must make the 5a group (number of men) as large as possible.
The first and simplest solution would be b = 0, a = 40. But this means there are no women and we must have men and women.
So next possible solution is b = 5, a = 36.
This minimizes the number of homeowners as 36 + 5 = 41
Answer (E)Integer solutions to equations in 2 variables are discussed here:
https://anaprep.com/algebra-integer-sol ... variables/Method 2:
You can do the same thing orally also. To minimize the number of homeowners, we must make the number of men as large as possible since only 20% of those are homeowners. Of the rest, 25% will be homeowners.
So we start with taking all 200 as men. But we must have some women too so we check whether 4 women are possible. No because that gives us 196 men which is not divisible by 5. Then check whether 8 women are possible. No.
Since number of men must be divisible by 5, we can have at most 180 men which gives us 20 women.
Number of homeowners = 180/4 + 20/5 = 41