I have attached the questions in those picture

1. Working for a car company, you have been assigned to nd the average miles per gallon (mpg) for a certain mode] of car. You take a random sample of 15 cars of the assigned model. Based on previous evidence and a QQ plot, you have reason to believe that the gas milage is normally distributed. You nd that the sample average miles per gallon is around 26.? with a population standard deviation of 5.2 mpg. (a) Construct and interpret a 95% condence interval for the mean mpg, a, for the certain model of car. (b) What would happen to the interval if you increased the condence level from 95% to 99%? Explain your reasoning. (Do not compute the new interval.) (c) The lead engineer is not happy with the interval you contructed and would like to keep the width of the whole interval to be less than 4 mpg wide. How many cars would you have to sample to create the interval the engineer is requesting? ((1) Suppose you are asked to repeat this process with data gathered from all across the country. You end up constructing a total of 60 separate 95% condence intervals at different factories for the estimated average mpg of the model of car. Of these intervals, how many of them do you expect would fail to contain the true value of a? 2. Suppose a computer engineer is interested in determining the average weight of a motherboard manufactured by a certain company. A simple random sample of 20 is provided to the engineer with the data given below. 12.25, 10.33,12.12,11.04,1211,1079,13.30,11.1s,12.7s, 12.25, 11.10,12.53,12.56,11.79, 13.56,12.4,11.54,13.75, 1147,1333 \f(c) Construct a 95% confidence interval as described in (b) and interpret the confidence interval. (b) Explain what confidence interval will you use and why. (a) Comment on the Normal Probability plot and boxplot. 10.5 11.5 12.5 13.5