Question

Doug entered a canoe race. He rowed 3 1/2 miles in 1/2 hour. What is his average speed in miles per hour ?

Answer 1

Doug's average speed is 7 miles per hour.

Explanation:

Average speed is defined as ratio of total distance to the total time taken to cover the total distance.

Distance covered by Doug ,D=
`3(1)/(2) miles=(7)/(2) miles`

Time taken to cover the distance D = T=
`(1)/(2) hour`

Average speed :

`=(D)/(T)=((7)/(2) miles)/((1)/(2) hour)=7 miles/hour`

Doug's average speed is 7 miles per hour.

Answer 2

3 1/2 miles = 7/2 miles
1/2 hours= 30 minutes
So,
In 30 mins, travelled 7/2 miles
In 1 min, travelled 7/2 ÷ 30= 7/2× 1/30 = (7×1)/(2×30) = 7/60 miles
In 60 mins, travelled (7×60)/60 miles = 420/60 miles = 7 miles.
Hence, the speed is 7 miles per hour.