A sample of 45 fridges is collected to give an indication of the approximate average weight of a fridge. The average weight from this sample is found to be 100kg. The population mean weight of these fridges is unknown, but the population standard deviation is thought to be 9.4 kg.

a) Create a 95% confidence interval for the mean weight of all fridges. SHOW YOUR WORKINGS, and give your answers correct to two decimal places.

b) Interpret your confidence interval.

c)Without calculating another confidence interval, and holding all else constant, would a 90% confidence interval be less precise than the 95% confidence interval you created in part a)? Briefly explain.