Question

Sandra swims the 100-meter freestyle for her school’s swim team. Her state’s ranking system awards 3 points for first place, 2 points for second, 1 point for third, and 0 points if she does not place. Her coach used her statistics from last season to design a simulation using a random number generator to predict how many points she would receive in her first race this season.

What is Sandra’s expected value of points awarded for a race?



Integer Value Points Awarded Frequency

1-8 3 20
9-15 2 12
16-9 1 6
20 0 2

Answer 1

2.25

Explanation:

The total frequency is:

20 + 12 + 6 + 2 = 40

Calculate the probability of each score:

P(X=3) = 20/40 = 0.50

P(X=2) = 12/40 = 0.30

P(X=1) = 6/40 = 0.15

P(X=0) = 2/40 = 0.05

So the expected value is:

E = (3)(0.50) + (2)(0.30) + (1)(0.15) + (0)(0.05)

E = 2.25