An appliance store is having a sale on refrigerators. The store has two models that are on sale: the basic model and the deluxe model. The basic model has a sale price of $1,200, and the deluxe model has a sale price of $2,500. Past data indicate that the basic model will have mean sales of 8.9 with a standard deviation of 1.8, while the deluxe model will have mean sales of 6.5 with a standard deviation of 2.2. You can assume these values are independent and Normal. Use this information to answer the questions.

1. Define random variables and use them to write a model that will return the total dollar amount the appliance store can expect to earn from refrigerators during this sale.
2. Use your model from part (a) to calculate the total dollar amount the appliance store can expect to earn from refrigerators during this sale. Show all your work.
3. Use your model from part (a) to calculate the standard deviation of the total amount the appliance store can expect to earn from refrigerators during this sale. Show all your work.
4. What is the difference in the expected number of basic and the expected number of deluxe refrigerators sold during this sale? What is the standard deviation? Show all your work.