1 Let X denote the note of bars of service on your cellphone

1. Let X denote the note of bars of service on your cellphone whenever you are at an intersection with the following probabilities:

x

0

1

2

3

4

5

f(x)

0.15

0.25

0.1

0.1

0.25

0.15

a) What is the probability that X is equal to 2 bars?

b) What is the probability that X is more than 3 bars?

Solution

a) (0.1)/(0.15 + 0.25 + 0.1 + 0.1 + 0.25 + 0.15) = 0.1

b) (0.25 + 0.15) / (0.15 + 0.25 + 0.1 + 0.1 + 0.25 + 0.15) = 0.4