Question

A number is picked from 1 to 20, both inclusive Find the probability that it is a prime.​

Answer 1

Let E be the event that the number picked from 1 to 20 is a prime and S be the sample space.

∴ n(S) = 20C1 = 20 E = {2, 3, 5, 7, 11, 13, 17, 19} n(E) = 8 P(E) = n(E)/n(S)  = 8/20  = 2/5