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Random Variables, Expectation & Variance · Question 50 of 68

Question 50

HardOriginal question

Two fair dice are thrown. What is the expected value of the sum of the two numbers?

Options for question 50

Show the answer and explanation
CorrectNot quiteAnswer D

Correct answer: D

Explanation

  1. The expectation of a sum is the sum of the expectations.

  2. Each die has expected value 3.5, so the sum has 3.5+3.5=73.5 + 3.5 = 7.

Worth noting

6.5 averages the possible sums 2 to 12 as plain numbers; 7 is also the most likely sum.

Concept
The expectation of a sum
Typical time
120 s
Your time
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The rule this testsMathematical expectation
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