Question

Find the probability that a number selected from the numbers 1 to 25 is not a prime number when each of the given numbers is equally likely to be selected.

Answer 1

Total no. of possible outcomes = 25 {1, 2, 3, ... 25}

E ⟶ event of getting a prime no.

No. of favourable outcomes = 9 {2, 3, 5, 7, 11, 13, 17, 19, 23}

Probability, P(E) =`"No.of favorable outcomes"/"Total no.of possible outcomes"`

= `9/25`

`(barE)` ⟶ event of not getting a prime no.

`P(barE ) = 1 - P(E)`

= `1 - 9/25`

= `16/25`