Question

A car covers a certain distance in 50 mins if it runs at 45 km/hr.how much time will it take to cover the same distance at 30 km/hr.

Answer 1

given speed = 45km/he
time = 50 min
therefore the distance= speed * time
= 45*50
=2250 Km
the time taken to cover 2250 KM in 30 km/he
= t=distance/speed
= 2250/30
= 75 min
= 1 hr 15 min

Answer 2

Given,

            Time taken to cover the distance = 50 mins = 50 * 60 = 3000 sec

           Travelling speed = 45 km/h = 45 * 5/18 = 12.5 m/s

             Imaginary speed = 30 km/h = 30 * 5/18 = 8.3 m/s

Let the distance be x.

We know,

               Speed = Distance/Time

By substituting values,

             ∴ 12.5 = x / 3000

             ⇒ 125/10 * 3000 = x

             ⇒ x = 125 * 300

             ⇒ x = 37500 m = 37.5 km

The time taken to cover 37.5 km at 30 km/h

Time= Distance/Speed

⇒ Time = 37.5/30 = 1 .25 hr  

Therefore it covers the same distance in 1.25 hours at the speed of 30 km/hr.