Question: 3/4 of all married couples have more than one child. 2/5 of all married couples have more than 3 children. What fraction of all married couples have 2 or 3 children?
Let the total number of married couples = the LCM Of 4 and 5 = 20.championspunch wrote:Question: 3/4 of all married couples have more than one child. 2/5 of all married couples have more than 3 children. What fraction of all married couples have 2 or 3 children?
A) 1/5
B) 1/4
C) 7/20
D) 3/5
E) Cannot be determined
Since 3/4 of all married couples have more than one child, the number of married couples with TWO OR MORE children = (3/4)20 = 15.
Since 2/5 of all married couples have more than 3 children, the number of married couples with FOUR OR MORE children = (2/5)20 = 8.
Thus, of the 15 couples who have 2 or more children, the number who do NOT have 4 or more children (in other words, the number WITH EXACTLY TWO OR EXACTLY THREE children) = 15-8 = 7.
Thus:
(couples with 2 or 3 children)/(total couples) = 7/20.
The correct answer is C.
