Respuesta :

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.

Answer:

Doug's average speed is 7 miles per hour.

Step-by-step 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=[tex]3\frac{1}{2} miles=\frac{7}{2} miles[/tex]

Time taken to cover the distance D = T= [tex]\frac{1}{2} hour[/tex]

Average speed :

[tex]=\frac{D}{T}=\frac{\frac{7}{2} miles}{\frac{1}{2} hour}=7 miles/hour[/tex]

Doug's average speed is 7 miles per hour.