Question

A car travels 90 km in 2 1/2hours.
(a) How much time is required to cover 30 km with the same speed?
(b) Find the distance covered in 2 hours with the same speed.

Answer 1

(a) In this case, time is unknown and distance is known. Therefore, we proceed as follows:

`2 1/2 "hours" = 5/2 "hours" = 5/2 × 60 "minutes" = 150 "minutes"`.

90 km is covered in 150 minutes.

Therefore, 1 km can be covered in `(150)/(90)` minutes.

Therefore, 30 km can be covered in `(150)/(90) × 30` minutes i.e., 50 minutes.

Thus, 30 km can be covered in 50 minutes.

(b) In this case, distance is unknown and time is known. Therefore, we proceed as follows:

Distance covered in `2 1/2 "hours (i.e.," 5/2` hours ) = 90 km.

Therefore, distance covered in 1 hour = 90 ÷ `5/2 "km" = 90 × 2/5` = 36 km.

Therefore, distance covered in 2 hours = 36 × 2 = 72 km.

Thus, in 2 hours, the distance covered is 72 km.