Question

A box contains 20 cards, numbered from 1 to 20. A card is drawn from the box at random. Find the probability that the number on the drawn card is a multiple of 3.

Answer 1

Given: A box contains cards numbered 1 to 20; one card is drawn at random.

Step-wise calculation:

1. Total possible outcomes = 20.

2. Favorable outcomes = Numbers ≤ 20 that are multiples of 3

= {3, 6, 9, 12, 15, 18}

⇒ Count = 6

3. Probability = `"Favourable"/"Total"`

= `6/20`

= `3/10`

= 0.3

The probability that the drawn card’s number is a multiple of 3 is `3/10` (30%).