## Problem

Jack picks at random three integers between 7 and 11 (inclusive). Mary picks an integer from 24 to 33 (inclusive). What is the probability that Mary’s number is less than the sum of Jack’s numbers ?

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Form is valid through October 2016

## Solution

Dear friends of the site. Thank you for your solutions.

The first to submit correct solutions were

Alexander Pappas and Yann Davies.Congratulations!

Thank you again and go ahead to solve the next problem!

Respectfully,

Serge Hazanov

Here is my solution:

The expected value of Jacks’ number is 9, so the expected value of the sum is 27.

The required probability is 3/10 = 0.3

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