Question

Brady rode his bike 70miles in 4 hours. He rode at an average speed of 17 mph for t hours and at an average speed of 22mph for the rest of the time. How long did Brady rode at a slower speed? Use the variable t to represent the time, in hours, Brady rode at 17mph.​

Answer 1

The Distance cover by Brandy rod at slower speed of bike is 61.2 miles .

Explanation:

Given as :

The total distance cover by Brady rode with bike = d = 70 miles

The total time taken by Brady rode with bike = 4 hours

The time taken for average speed of 17 mph = t hours

Let The time taken for average speed of 22 mph = (4 - t) hours

Let The distance cover for slower speed = d miles

Now, From formula

Distance = speed × time

So, Total distance cover = distance at slower speed + distance at faster speed

Or, 70 miles = 17 mph × t hours + 22 mph × (4 - t) hours

Or, 70 = 17 t + 22 × 4 - 22 × t

or, 70 = 88 + 17 t - 22 t

or, 22 t - 17 t = 88 - 70

or, 5 t = 18

∴ t =
`(18)/(5)`

i.e t = 3.6 hours

So, The time taken for average speed of 17 mph = t = 3.6 hours

And The time taken for average speed of 22 mph = (4 - 3.6) = 0.4 hour

So, Distance cover at slower speed = slower speed × time at slower speed

i.e d = 17 mph × 3.6 h

Or, d = 61.2 miles

So, Distance cover at slower speed = d = 61.2 miles

Hence, The Distance cover by Brandy rod at slower speed of bike is 61.2 miles . Answer