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 Probability

1 0.2

2 0.3

3 0.4

4 0.1

a) How many calls should the shop expect perhour?

The shop should expect ( integer or a decimal. Do notround.)

b) What is the standarddeviation?

The standard deviation is( integer or a decimal. Do notround.)