Statistics

2. A company has a policy of retiring company cars; this policy looks at number of miles driven, purpose of trips, style of car and other features. The distribution of the number of months in service for the fleet of cars is bell-shaped and has a mean of 55 months and a standard deviation of 4 months. Using the empirical rule (as presented in the book), what is the approximate percentage of cars that remain in service between 63 and 67 months? Do not enter the percent symbol. ans = 95 3. In a mid-size company, the distribution of the number of phone calls answered each day by each of the 12 receptionists is bell-shaped and has a mean of 42 and a standard deviation of 8. Using the empirical rule (as presented in the book), what is the approximate percentage of daily phone calls numbering between 34 and 50? Do not enter the percent symbol. ans = 96 For a standard normal distribution. nd: P(-2.48 -2.68) 6. The annual rainfall in a certain region is approximately normally distributed with mean 41.5 inches and standard deviation 5.8 inches. Round answers to the nearest tenth of a percent.| a) What percentage of years will have an annual rainfall of less than 44 inches? 96 b] What percentage of years will have an annual rainfall of more than 38 inches? 96 c) What percentage of years will have an annual rainfall of between 37 inches and 43 inches? 7. Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0"C and a standard deviation of 1.00\"C. A single thermometer is randomly selected and tested. Find P., the 1-percentile. This is the temperature reading separating the bottom 1% from the top 99%. P| = \"C 8. Assume that the readings at freezing on a batch of thermometers are normally distributed with a mean of 0C and a standard deviation of 1.00\"C. A single thermometer is randomly selected and tested. Find P35, the 35-percentile. This is the temperature reading separating the bottom 35% from the top 65%. P35: DC