Starting at home, Ishaan traveled uphill to the grocery store for 12 minutes at just 15 mph. He then traveled back home along the same path downhill at a speed of 30 mph.
What is his average speed for the entire trip from home to the grocery store and back?
His average speed will be the total distance he traveled divided by the total amount of time it took him.
Find his total distance:
12 minutes is 12/60 hours, or 0.2 hours.
He went 15 mph for 0.2 hours, so the distance to the grocery store is 15(0.2) = 3 miles.
He went to the grocery store and back twice so his total distance was 3(2) = 6 miles.
Find his total time:
The first trip was 12 minutes.
He went twice as fast on the second trip so his time will be half as much. 12/2 = 6 minutes.
His total time is 12 + 6 = 18 minutes.
Average speed = 6 miles / 18 minutes
Average speed = 1/3 miles per minute.
Average speed = 20 miles per hour.
Very nicely explained hectictar
I'd give you more points if I could. Hopefully Athena will give you some points (stars) too :))