Two cars start together from the same place in same direction. The first goes with unifrom speed of 60 km/hr. The second goes at a speed of 48km/hr in the first hour and increases the speed by 1km each succeding hour. After hour and many hours will the second car overtake the first car if both cars go non-stop?

Answer

25 hours

Explanation

Suppose the second car overtakes the first car in n hours.
Distance covered by the first car in n huours = ( 600n ) km
Distance covered by the second car in n hours
[ 48+49 +50 +….. To n terms]
` n/2 xx [ 2xx 48+ (n-1) xx1] =n/2 (95+n)`
`n/2 ( 95 +n) = 60n Rightarrow 95+n 120 Rightarrow n = 25` hours.