# Science:Math Exam Resources/Courses/MATH105/April 2012/Question 08 (e)

MATH105 April 2012
Other MATH105 Exams

### Question 08 (e)

Short-answer questions. No credit will be given for the answer (even if it is correct) without the accompanying work.

There are two boxes containing two balls each. The balls in the ﬁrst box are numbered −1 and 1, the balls in the second box are numbered 0 and 2. An experimenter draws a ball from each box and observes the number of each ball. Deﬁne a random variable X whose value is two times the number of the ball drawn from the ﬁrst box plus three times the number of the ball drawn from the second box. In other words,

X = 2(number observed from box 1) + 3(number observed from box 2).

Write down all possible values of X and use this to compute the expected value of X.

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