68-95-99.7 Rule

1. The physical plant at the main campus of a large state university recieves daily requests to replace fluorescent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 42 and a standard deviation of 6. Using the empirical rule (as presented in the book), what is the approximate percentage of lightbulb replacement requests numbering between 36 and 427 2. The number of potholes in any given 1 mile stretch of freeway pavement in Pennsylvania has a bell-shaped distribution. This distribution has a mean of 62 and a standard deviation of 5. Using the empirical rule (as presented in the book), what is the approximate percentage of 1-mile-long roadways with potholes numbering between 52 and 67? 3. 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 64 months and a standard deviation of 5 months. Using the empirical rule (as presented in the book), what is the approximate percentage of cars that remain in service between 69 and 74 months? 4. The physical plant at the main campus of a large state university recieves daily requests to replace fluorescent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 49 and a standard deviation of 11. Using the 68-95-99.7 rule, what is the approximate percentage of lightbulb replacement requests numbering between 2/ and 49? 5. A company has a policy of retiring compary 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 59 months and a standard deviation of 8 months. Using the 68-95-99.7 rule, what is the approximate percentage of cars that remain in service between 35 and 43 months