# Easy Probability Solved QuestionAptitude Discussion

 Q. What is the probability that a number selected from numbers 1,2,3,...,30, is prime number, when each of the given numbers is equally likely to be selected?
 ✖ A. 9/30 ✖ B. 8/30 ✔ C. 10/30 ✖ D. 11/30

Solution:
Option(C) is correct

$X = \{2,3,5,7,11,13,17,19,23,29\}$

$n(X)= 10, n(S)=30$

Hence required probability,

$= \dfrac{n(X)}{n(S)}$

$= \dfrac{\textbf{10}}{\textbf{30}}$

## (1) Comment(s)

Puskar
()

Prime numbers from 1 to 30 = ( 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 )

P( a prime number) = 10C1/30C1