What is the smallest number of science students who could be studying biology

Question

If 20% of the science students at central high study only physics, 25% study only chemistry and the rest study only biology, what is the smallest number of science students who could be studying biology?

 

A. 4

B. 9

C. 11
D. 15

Answer 1

1 - .25 - .20 = .55 study bio

 

So, 55/100 = 4/x  x - 7.273, not a whole number

 

55/100 = 11/x  not a whole number

 

55/100 = 11/x  x = 20, a whole number!  this is the answer!