Question 4. (a) (b) A statistics student was interested in investigating the average time it takes to get a pizza delivered to their house from the local pizzeria. Over a few weeks, a random sample of 10 delivery times (in minutes) was recorded. The data are displayed below: 19.9, 23.2, 24.4, 20.3, 1?.3, 23-1: 13.7, 243}, 31.5r 22.3 Summary statistics: f = 23.09 minutes and s = 4.31. Calculate and interpret a 95% condence interval for the mean delivery time. Note: You must clearly show that you have followed the \"Step-by-Step Guide to Producing a Condence Interval by Hand\" given in the Lecture Workbook, Chapter 6. Use the r-procedures tool to nd values for the t-multiplier and the standard error. The student believes that, on average, pizzas from this pizzeria take less than 25 minutes to arrive. Does the data support this? Briey justify your answer. Step-by-Step Guide to Producing a Confidence Interval by Hand 1. State the parameter to be estimated. (Symbol and words) Is it u, P, M1 - 12, or p1 - P2? 2. State the estimate and its value. 3. Write down the formula for a Cl, estimate + txse(estimate), from the Formula Sheet 4. Use the appropriate standard error. (Will be provided) 5. Use the appropriate t-multiplier. (Will be provided) 6. Calculate the confidence limits. (End points of the confidence interval) 7. Interpret the interval using plain English. Use the confidence limits to construct an answer to the original question in plain English