A parking garage has two entrances Let X be the number of ca

A parking garage has two entrances. Let X be the number of cars that enter the garage through door A in an hour, and Y be the number of cars that enter through door B in an hour. Assuming that _X = 15 and _Y = 25, what is the mean of Z, the total number of cars that enter the garage in an hour?

A - 10

B- 15

C- 25

D- 40

Solution

As

Z = X + Y

Then

uZ = uX + uY

uZ = 15 + 25 = 40 [ANSWER, D]