JAMB Mathematics 2020 Paper

Concept:Probability is the ratio of favourable outcomes to total possible outcomes.Explanation:The numbers from 20 to 30 inclusive are: 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30.Thus, the total number of possible outcomes is $11$.A prime number has only two factors: 1 and itself.The prime numbers in this range are $23$ and $29$.So the number of favourable outcomes is $2$.Therefore, probability $= \frac{\text{Number of primes}}{\text{Total outcomes}} = \frac{2}{11}$.Answer:$\frac{2}{11}$Option A.