Probability
Aptitude

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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

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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,

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

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


(2) Comment(s)


Saravana
 ()

y is 1 not selected as prime number??



Puskar
 ()

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

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