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 0.3 0.1

a. How many calls should the shop expect per hour?
b. What is the standard deviation?

a) So, she can expect a 2.4 calls per hour.

b) So, the standard deviation is 0.8.

Step-by-step explanation:

We know that probability model below describes the number of repair calls that an appliance repair shop may receive during an hour.

Repair Calls 1 2 3 4  

Probability 0.1 0.5 0.3 0.1

a) We calculate how many calls should the shop expect per hour.

We get:

So, she can expect a 2.4 calls per hour.

b) We calculate the standard deviation:

So, the standard deviation is 0.8.

could you provide figure.