Aiden drives to school and back each day. the school is 16 miles from his home. he averages 40 miles per hour on his way to school. if his total trip takes 1 hour, at approximately what average speed does aiden drive

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?