1.In a random sample of 40 refrigerators, the mean repair cost was $150. Assume the population standard deviation σ = $15.5.a. Construct a 99% confidence interval for the population mean repair cost. Interpret the interval in the context of the problem. [Use Algebra]b. Repeat exercise 1(a), changing the sample size to n = 60. Which confidence interval has better estimate? Why? Explain? [Use Algebra]c. Repeat exercise 1(a), using a population standard deviation of σ = $19.5. Which confidence interval is wider? Explain? [Use Algebra]