A probability problem by hritik raj
Probability
Level
2
If 56 % of students failed in one subject and 48% failed in other and 18% failed in both, Find % students passed in both
The answer is 14.
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1 solution
I use set theory to deal with this problem.
Let 'A' =56-----------------------(no. of students who failed in 1st sub)
'B'=48------------------(no. of students who failed in 2nd sub)
'A' intersection 'B'=18-----------------(no of students who failed in both)
We need to find (A U B)'------------------(('A' union 'B') compliment or the number of students who passed in both sub) i.e (A U B) denotes the number of students who failed in atleast one subject.
Using the standard formulas of sets
(A U B)'= 100 - (A + B - (A intersection B ))
( A U B)'=100 -(56+48-18)
=14