In a class of 125 students 70 passed in Mathematics, 55 in statistics, and 30 in both. Then find the probability that a student selected at random from the class has passes in only one subject.

Answer

`13//25`

Explanation

Consider the following events:
A: A student is passed in Mathematics
B: A student is passed in Statistics
Then,
`P(A) = (70)/(125), P(B) = (55)/(125), P(A nn B) = (30)/(125)`
Required probability is
`P(A nn barB) + P(barA nn B)`
`=P(A) + P(B) - 2P(A nn B)`
`=(70)/(125) + (55)/(125) - (60)/(125) = (65)/(125) = (13)/(25)`