Question

A small train at an amusement park is carrying passengers. Half of the passengers are 4 years old, 1/10 are 5 years old, 3/10 are 6 years old, and 1/10 are 7 years old.
What is the expected age for one of the passengers on the train?

A. 5 years
B. 5.5 years
C. 6 years
D. 6.1 years

Answer 1

In order to find the expected age, we must multiply the probability of picking each child by their age, then add them all up. Like this:

E(x) = 4(1/2) + 5(1/10) + 6(3/10) + 7(1/10)
E(x) = 5 years

By doing this we are giving each age group a percentage of the entire population.

Hope this helps!