Question

One car travels 25 km/h faster than another. In the same time that one goes 120 km, the other goes

220 km. Find their speeds.

Answer 1

Speed of first car = 30 km/h and speed of second car = 55 km/h

Explanation:

Speed = distance/time

Given: distance travelled by one car = 120 km

Distance travelled by second car = 220 km

Now let speed of first car be x km/h.

∴ Speed of second car = (x + 25) km/h (∵ One car travels 25 km\h faster than another)

Now, if the time is constant, then ratio of distance to speed of first car will be equal to the ratio of distance to speed of another car. e.g.,

`(distance\ travelled\ by\ first\ car)/(speed\ of\ first\ car) = (distance\ travelled\ by\ second\ car)/(speed\ of\ second\ car)`

`(120)/(x) = (220)/(x+25)`

`220x = 120 (x +25)`

`220x = 120x + 3000`

`100x = 3000`

`x = 30`

∴ Speed of first car = 30 km/h

Speed of second car = (30 + 25) = 55 km/h.