Question

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

Answer 1

Let $E$ be the event of getting a not-a-prime number in the event of selecting from the numbers $1$ to $25$

Non-Prime numbers upto $25=1,4,6,8,9,10,12,14,15,16,18,20,21,22,24,25$
No. of favorable outcomes$=16$

Total no. of possible outcomes $=25$

We know that, Probability $P\left(E\right)$ $=\frac{\text{(No.of favorable outcomes)}}{\text{(Total no.of possible outcomes)}}$$=\frac{16}{25}$

Therefore, the probability that the drawn ticket bears a prime number is $=\frac{16}{25}$