Let us suppose there are 100 people. 40% of them donated $16000 ( 400 * 40 )
$16000 is 60% of total amount.
So total amount = 16000 * 100/60
Remaining amount is 40% of total amount.
40% of total amount = 16000 * (100/60) * (40/100) = 32000/3
This amount has to be divided by 60 ( remaining people are 60 )
So per head amount is 32000/3 / 60 = 32000/180 = 1600/9 = $177.78
Please give a kudo if you like my explanation.
I have read somewhere in MGMAT books
that we should not assume any quantity in the question to be 100 when any specific values are given. Here 16000 $ is given. In fact we are required to calculate a specific value too. Thats y I assigned variables to the unknown and could solve the problem albeit consuming a little more time. As per the explanation however it seems perfectly fine to assume one of the quantities to be 100 and still the answer does not change.
Can someone help me out here