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A number is selected at random between 20 and 30, both nu...

A number is selected at random between 20 and 30, both numbers inclusive. Find the probability that the number is a prime

A.

211

B.

511

C.

611

D.

811

Correct answer is A

Possible outcomes are 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. Prime numbers has only two factors

itself and 1

The prime numbers among the group are 23, 29. Probability of choosing a prime number

= Number of primeNo. of total Possible Outcomes

= 211