John went on a bike ride to the store 4 miles away. If it took John 3/10 of an hour to get there and 1/2 of an hour to get back, what was his average rate of speed (miles per hour) for the entire trip?

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.