Posted by Jerry on .
100 students were asked whether they are taking psychology or biology. 61 were taking pyschology, 18 were taking both and 12 were taking neither. how many were taking biology?

Math 
Reiny,
Make a Venn diagram with two intersecting circles
label "only biology" as x
place 18 in the intersection
place 43 in the "only psychology"
place 12 outside the two circles
x + 18 + 43 + 12 = 100
x = 27
So Biology was taken by 27+18 or 45 students