The salespeople at Quality Motor Bikes sell up to 5 bikes a

The salespeople at Quality Motor Bikes sell up to 5 bikes a month. The probability distribution is as follows in the table below. What is the variance of bikes sold during a month?

2.60

2.02

3.15

1.40

1.18

Solution

mean= E(X)= sum of x*f(x)

=0*0.02+1*0.4+2*0.3+3*0.15+4*0.08+5*0.05

=2.02

E(X^2) = 0*0.02+1*0.4+2^2*0.3+3^2*0.15+4^2*0.08+5^2*0.05

=5.48

So variance= E(X^2) -[E(X)]^2

=5.48-2.02^2

=1.3996

Answer: 1.40