Mrs Tienda has a small shop in the village of Overford, she sells a variety of groceries. Tesbury Superstore has just opened up on the edge of the village.

Mrs Tienda has put a sign up in the window of her shop that says "Buy your food here - we’re cheaper than Tesbury’s".

Below is a list of foods and their prices. The same products were bought in Mrs Tienda’s shop and Tesbury’s Superstore.

1. Time to make a prediction

Look at the figures above, and without using a calculator, make a prediction about which shop is cheaper.

I predict that ___________________________________is cheaper.

2. Now it’s time to find out if you are right.

(a) What type of software are you going to use to find out which shop is cheaper?

(b) Now use this software and find out if your prediction is correct.

Did you make the correct prediction?

(c) How did you find out which shop was cheaper?

(d) Why is the software that you chose useful for solving this type of problem?

(e) How would you have solved the problem without using a computer?

Mrs Tienda wants to use a computer to produce receipts for customers.

The computer needs to calculate:

The total cost of the goods bought.

The amount of change that needs to be given to the customer.

1. Use the data below to help you to produce a receipt:

(a) Check the prices to make sure they have been entered correctly. Have you entered them correctly?

(b) What was the total cost of the goods bought in week one?

(c) The customer paid using a £20 note.

How much change will he receive?

2. Mrs Tienda decides to increase the prices (see below).

(a) Change the prices in your model according to the data for Week 2.

(b) Check the prices to make sure they have been entered correctly. Have you entered them correctly?

(c) What was the total cost of the goods bought in week two?

(d) The customer paid using a £20 note.

How much change will he receive?

(e) Explain how you used the software to help you to complete this task.

(f) Explain how the tills are used in a superstore, such as Tesbury’s. Include information about the equipment used.

Mrs Tienda wants to keep a record of how much stock is sold each day.

Create a computer model that allows you to enter stock sold of the items listed below.

Your model must allow you to:

enter stock data (how many there are of each item) relating to the foods above.

calculate the amount of profit assuming that each food is sold for 20 % more than the cost price (the price that the supermarket paid for the food).

Calculate the total profit.

1. If you sold 200 jars of Coffee, how much profit would you make on coffee?

2. If you sold the quantities shown below, how much sunflower oil would you have to sell to make approximately £400 profit in total?

Tesbury superstore has 12 checkouts.

They use a computer based model to work out the longest time a customer has to queue at a checkout.

These are screen displays from the model.

(a) Fill in the values that the model should produce.

(b) Your task is to use a computer to design this model. Your model will allow you to enter figures for:

• Total number of customers waiting.

• Number of checkouts being used.

• Average time to process one customer at a checkout.

The model will then calculate:

• Average number of customers at each checkout.

• The longest time a customer has to wait.

Use a suitable type of software to write your answers to the following questions:

(c) The manager of the superstore says that she doesn’t want customers queuing for more than 5 minutes. If all the checkouts are being used how many waiting customers can the superstore deal with? She has timed the average time that customers take at 2 minutes.

Explain carefully how you answered this question using your model.

(d) The superstore would like to expand and be able to deal with 100 waiting customers. How many checkouts will they need? She has timed the average time that customers take at 2 minutes and no customer may wait for more than 8 minutes. Explain carefully how you answered this question using your model.

(e) Why might the model produce incorrect figures in a real superstore?