A water tank salesperson wanted to research the linear relationship between household annual water bill ($), the number of people per household and the capacity of a backyard water tank (litres) of that household. Only households with water tanks were sampled. The sales person took a random sample and used Excel to create the following regression output.

a) Write down the regression equation.

b) Interpret the coefficient of backyard water tank capacity.

c) Using the 10% significance level, test whether this is a significant negative linear relationship between annual water bill and backyard water tank capacity; give hypotheses, your reasoning, decision, and conclusion.

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