xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Question 1 A survey of 30 supermarkets reported these numbers of sales held during a randomly selected year. Number of Sales Frequency 8-12 13-17 18-22 23-27 28-32 33-37 1 4 10 5 4 6 A. Calculate the standard deviation of the frequency distribution. B. Construct a percentile graph. Use it to approximate the median and upper quartile. Question 2 A random sample of 16 mid-sized cars tested for fuel consumption gave a mean of 26.4 kilometers per litre with a standard deviation of 2.3 kilometers per litre. A. Assuming that the kilometers per litre given by all mid-sized cars have a normal distribution, find a 99% confidence interval for the population mean . B. Suppose the confidence interval obtained in (a) is too wide. How can the width of this interval be reduced? Describe all possible alternatives. Which alternative is the best and why