1Suppose that the duration of trouble-free operation of a new vacuum cleaner is normally distributed with a mean of 72 weeks and variance of 144 weeks². The research department randomly selects 25 customers who bought these vacuum cleaners and records duration (in weeks) of trouble-free operation.

A.The standard error of the sample mean isweeks (1 decimal place).

B.The probability that the average duration of trouble-free operation time is between 75 weeks and 78 weeks is(4 decimal places).

QUESTION 10 Consider the following descriptive statistics from Excel for a sample of bread loaf weights (in grams) baked in a Brisbane bakery. Median 451 Standard Deviation 210.7663 Sample Variance 44422.44 Range 785 Minimum 264 Maximum 1049 Sum 6155 Count 13 What is the 95% confidence interval for the population mean weight of a bread loaf baked in this bakery? Ca. 438.14