The probability model below describes the number of repair calls that an appliance repair shop may receive during an hour. Complete parts a and b below.

Repair Calls

1

2

3

4

Probability

0.1

0.5

0.2

0.2

a) How many calls should the shop expect perhour?

The shop should expect

nothing

calls per hour.

(Type a integer or a decimal. Do notround.)

b) What is the standarddeviation?

The standard deviation is

nothing.

(Round to two decimal places asneeded.)