Question

There are 9 flash cards with numbers from 20 to 28 written on them. Laura drew the card with 22 on it. She is about to draw another card. What is the probability that the sum of the numbers on these two cards will be a multiple of 5?

Answer 1

1 /4

Explanation:

Multiples of 5 = (5, 10, 15, 20, 25, 30, 35, 40, 45)

Numbers on card : (20,21,22,23,24,25,26,27,28)

Number on first card = 22

To have a sum which is a multiple of 5 ; number on second card must be either :

23 or 28

22 + 23 = 45

22 + 28 = 50

Since only 2 of the cards will. Result in a sum which is a multiple of 5

Required outcome = 2

Total possible outcomes = (9 - 1) = 8

Probability = required outcome / Total possible outcomes

= 2 / 8

= 1 /4