Question

In an examination, 70% of students passed in physics, 65% in chemistry, 7% failed in both subjects. the percentage of students who passed is:

a.66%

b.62%

c.69%

d.none of these

Answer 1

None of these.
Percentage who passed = 100 - (70+65+7) = 100 - 142 = 42%

Alternatively:
Failed in physics = 30%
Failed in chemistry = 35%
Failed in both = 7%
Failed only in physics = 30-7 = 23%
Failed only in chem = 35-7 = 28%
Passed = 100- (23+28+7) = 100 - 58 = 42%