A store sells pre-cut lengths of materials. A customer wants to determine if there is a linear relationship between the price ($/metre) and length (metres) of the materials. The customer takes a random sample of materials for sale and records the price and length.

Excel was then used to create a simple linear regression of price on length. Here is a table of the sample data, with the Excel regression output:

a) Write the estimated simple linear regression equation, using the names of the variables.

b) Interpret the slope for the customer.

c) Estimate the price of materials that is pre-cut to 1,000 metres in length. Comment on the reliability of your estimate.