Expert: Lynn Houston - 6/10/2009

Question
In a certain examination 35 percent of the students failed in Mathematics and 20 percent failed in Chemistry.10 percent of students failed in both Mathematics and Chemistry .Find the number of students who failed only in chemistry, if the number of students passing in both the subjects is 110.

Answer
I might be missing something, but if 10% failed in both (ie 90% passed both) and there are 110 that passed both, then the total number of students must be 122 (.9x = 110, where x = total # of students).  Then just take 20% of 122 = ~24 students failed chem.