Traveling 15 miles in 20 minutes, how many miles per hour must you be going?

45

Step-by-step explanation

Juan has just completed a 15 kilometer race in 20 minutes.  What was his average speed in kilometers per hour?

Solution

First, 15 kilometers is a distance, so

       d  =  15

Next, we are given 20 minutes and we are asked to present the speed in kilometers per hour rather than kilometers per minute.  We need to convert 20 minutes to hours.  Since there are 60 minutes per hour, we divide by 60 to find out how many hours it took

t  =  20 minutes / 60 minutes per hour =  1/3 hours

Now we can use the d=rt equation:

15  =  (r)(1/3)

If we multiply both sides

(3)(5)  =  (r)(1/3)(3)  or  r  =  45

Juan's average speed was 45 kilometers per hour.