Everyday Math for 12-24-08

This one came from my oldaer son. He observed that we travelled 1 mile in 46 seconds. The question was, how fast is that in mph?

Our speed was 1 mile / (per) 46 seconds. Which is 1/46 miles per second or .02173913 miles per second. Mulitply that by 60 to get miles per minute. Multiply that by 60 to get 78.2 miles per hour.

Another question was "If we're going 70 mph, how long will it take to go 51 miles?

Put the unit type you want on top (time, distance, etc)

1 hour per 70 miles or 1 hour/70miles times 51 miles or 1X 51/ 70 or .72857143 hours (the miles cancel each other out). Multiply that times 60 minutes per hour to get 43.714 minutes. For comparrison, 80mpg gives you 39 minutes. And 500mph gives you 6.2 minutes.