only first one is enough cause if they are equal, then the total average should be 165. but since it is smaller than 165, number of females should be larger than number of males
dsaqwert, could you please explain further.
My answer is A
My approach:
Females/x = 160, where x is the number of females -> females' height is 160x
males/y= ?, where y is the number of males
females+males/x+y=164
from statement 1: males/y=170 -> males' height=170y
160x+170y/x+y =164
160x+170y=164x+164y
4x=6y
x=3/2 *y
Consequently, x>y, i.e. number of females is bigger than that of males -> statement 1 is enough
Statement 2 is not enough as we don't know the combined height or the average or the number of males.
ok, let;s make it more clear;Originally Posted by Jeeves
assume number of boys and girls are equal, and knowing that the average of girls is 160 and the average of boys is 170, what overall average would you expect.... yes 165 ([160x + 170x]/2x=165) however the overall average is 164, in other words number of girls should be more than number of boys to ensure that the overall average is closer to the girls' average
in other words (mathematically);
x=number of girls
y=number of boys
160x+170y=164(x+y)
6y=4x
x=1.5y
x>y
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