It takes 15 min to run 2/3 of a mile. How long does it take to run 3 miles?

Question

It takes 15 min to run 2/3 of a mile. How long does it take to run 3 miles?

Answer 1

Jennifer,  Let x= unknown minutes in 3 miles.  So the ratio is 15 minutes/2/3 miles x 3 miles/x.  miles cancel,  leaving 15 x 3/2/3x;  multiply both sides by the reciprocal of 2/3 which is 3/2;  so:  x=135/2= x=67.5= 1hr  7min  30sec

 

 

 

Answer 2

The rate is constant.

 

Rate =   (15 min) / (2/3 mile)

          (15 min)*(3)/(2 miles)

          (45/2 minutes/mile)

 

How long to run 3 miles?

         (45/2 minutes/mile)*(3 miles)

         (135/2 minutes)             [note: miles cancels out]

         67.5 minutes

        1 hour 7 minutes 30 seconds