Aptitude 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,

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

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

**Saravana**

*()
*

**Puskar**

*()
*

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

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

y is 1 not selected as prime number??