Question

Cards numbered 1 to 30 are put in a bag. A card is drawn at random from the bag. Find the probability that the number on the drawn card is a prime number greater than 7.

Answer 1

Let E₂ be the event of getting a prime number greater than 7.

Out of these numbers, prime numbers greater than 7 are 11, 13, 17, 19, 23 and 29.

Number of favourable outcomes = 6

∴ P(getting a prime number greater than 7) = P(E₂) = `("Number of outcomes favourable to" E_2)/"Number of all possible outcomes"`

`= 6/30 = 1/5`

Thus, the probability that the number on the card is a prime number greater than 7 is `1/5`.