Question

There are ten cards, each has a different number on it, from 1 to 10. Sam took one card, and it was 5 on it. If he takes one of the remaining cards without looking, what is the probability that the sum of the numbers on his two cards will be smaller than 8?

Answer 1

2/9

Explanation:

The original group of cards consisted of: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

He took a 5.

The current group of cards consists of: 1, 2, 3, 4, 6, 7, 8, 9, 10

Which cards can he take and have a sum less than 8?

5 + 1 = 6 good

5 + 2 = 7 good

5 + 3 = 8 not good

Only the cards with 1 or 2 are good.

There are 9 cards remaining, and he gets the desired outcome from only 2 of those cards.

p(sum less than 8) = 2/9

Answer 2

there are 9 cards left

1,2,3,4,6,7,8,9,10

the only cards that will make the sum less than 8 is 1 and 2

2/9

Answer: 2/9