The data below gives the mean price (in cents) of a litre of regular gasoline at self-service filling stations at a sample of six urban centres in Canada in May 2013. Urban area Price/litre Charlottetown 126.6 Halifax. 126.3 Montreal 135.9 Regina 123.7 Saskatoon 125.2 Vancouver 145.7 Provide answers to the following to two decimal places. You may calculate your answers using: (1) a calculator and Table IV; or (ii) Minitab. Part (a) Find the sample mean (in cents). Part (b) Find the sample standard deviation (in cents). Part (c) Using the appropriate t distribution, find a 90% confidence interval for the mean gasoline price per litre across urban Canada in May 2013. Provide the upper and lower bounds for your confidence interval. ( Part (d) Would a 95% confidence interval be wider or narrower than the interval you found in Part (c)? Using the appropriate t distribution, find a 95% confidence interval for the mean gasoline price per litre across urban Canada in May 2013. Provide the upper and lower bounds for your confidence interval. (