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Homework answers / question archive / The probability density function of the random variable X is given by f ( x )=1/40 for 20 < x < 60 , and zero elsewhere
The probability density function of the random variable X is given by f ( x )=1/40 for 20 < x < 60 , and zero elsewhere . The expected value , E ( X ) , of the random variable X is :
Select one :
a.5
b.28
c.15
d.30
e.None of the answers is correct
Expected value = 
x * f(x)
Expected value = 1 * 0 + 2 * 0 + 3 * 0 + ...... + 20 * 0 + 21 * (1 / 40) + 22 * (1 / 40) + .......... + 59 * (1 / 40) + 60 * 0 + 61 * 0 ..........
Expected value = 21 * (1 / 40) + 22 * (1 / 40) + .......... + 59 * (1 / 40) = [(21 + 22 + 23 + 24 + ........ + 59) / 40] = (1,560 / 40) = 39
Option E is correct.
