Out of first 20 natural numbers, one number is selected at random. The probability that it is either an even number or a prime number is_____________?

A. 1/2
B. 16/19
C. 4/5
D. 17/20

Explanation:

n(S) = 20

n(Even no) = 10 = n(E)
n(Prime no) = 8 = n(P)
P(EᴜP) = 10/20 + 8/20 – 1/20 = 17/20