Question

At an examination, students can select three subjects out of many subjects. The following information is given on the subjects STATS and IT and MATHS.

45% of all students take MATHS
20% take IT and STATS but not MATHS
5% take IT and MATHS but not STAT
90% take at least one of STATS, IT and MATHS
10% take STATS and MATHS but not IT
20% take only MATHS
50% take STAT

What is the percentage of students who take STATS and MATHS and IT.

Answer 1

Becomes real simple if you use Venn diagrams
I placed x in the intersection of M, I, and S. ( x will be the solution to your question)
I filled in the following:

10% take STATS and MATHS but not IT
5% take IT and MATHS but not STAT
20% take only MATHS

I then used: 45% of all students take MATHS
to form the equation
x+10+5+20 = 45
x = 10

Answer 2

Thanks Reiny