Question B6 Market researchers want to estimate the mean monthly expenditure on transport for households in Sydney. The researchers want to calculate the 95% confidence interval of the mean. They randomly selected 40 householders and asked their expenditure on transport over the past month. The sample mean is $350. The population standard deviation is known to be $200. 1) Should the t distribution or z distribution be used to calculate the confidence interval? Give your reasons. Click or tap here to enter text. 2) Calculate the lower limit and upper limit of the 95% confidence interval. Lower limit: Click or tap here to enter text. Upper limit: Click or tap here to enter text. 3) If the sample size is 10, can you still calculate the confidence interval with t or z distribution? Give your reason