Probability Answers

Probability - Quant/Math - CAT 2008

Question 4 the day: March , 2003

The question for the day is from the topic of Probability

When two dice are thrown simultaneously, what is the probability that the sum of the two numbers that turn up is less than 11?

(1)	5 / 6			(2)	11 / 12
(3)	1 / 6			(4)	1 / 12

Correct Answer - (2)

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Solution:


Instead of finding the probability of this event directly, we will find the probability of the non-occurrence of this event and subtract it from 1 to get the required probability.

Combination whose sum of 12 is (6,6)

Combinations whose sum of 11 is (5,6), (6,5).

Therefore, there are totally 3 occurrences out of 36 occurrences that satisfy the given condition.

Probability whose sum of two numbers is greater than or equal to 11 = 3 / 36 = 1 / 12.

Hence probability whose sum of two numbers is lesser than 11 = 1 - 1 / 12 = 11 / 12.