JAMB - Mathematics (2020 - No. 22)
A number is selected at random between 20 and 30, both numbers inclusive. Find the probability that the number is a prime.
\(\frac{2}{11}\)
\(\frac{5}{11}\)
\(\frac{6}{11}\)
\(\frac{8}{11}\)
Spiegazione
Possible outcomes are 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30. Prime numbers have only two factors, itself and 1. The prime numbers among the group are 23, 29.
The probability of choosing a prime number
= \(\frac{\text{Number of Prime}}{\text{No. of Total Possible Outcome}}\)
= \(\frac{2}{11}\)