Question

A car travelling at 60 km/hr left Dehradun at 3 P.M. One hour later, another car travelling at 80 km/hr started over the same road to overtake the first. How long must the second car travel to overtake the first car.

Answer 1

Answer:

3 hours

Step-by-step explanation:

Let the second car overtake the first, x hours after it started.

First car travelled for (x + 1) hours.

Distance covered by both the car is same.

Distance covered by first car in (x + 1) hours = 60(x + 1) km

Distance covered by second car in x hours = 80x

∴ 60(x + 1) = 80x

⇒ 60x + 60 = 80x

⇒ 60 = 80x - 60x

⇒ 60 = 20x

⇒ $\bold{\dfrac{60}{20}}$ = x

⇒ 3 = x

Hence, the second car travelled in 4 hours.

Answer 2

$<b>$Solution:-

Let the Second Car Overtake the First Car in "x" hours.

Since, First car started before an hour.

=> First Car Travelled for (x + 1) hours.

A.T.Q.

Distance Travelled by 1st Car in (x+1) hour = 60 (x+1) km.

& Distance Travelled by Second Car in x hours = 80x km.

Since, Both the Car will meet.

Therefore, Distance Travelled by both Car will be same.

=> 60 ( x+1) = 80x

=> 60x + 60 = 80x

=> 60 = 80x - 60x

=> 20x = 60

=> $\boxed{x = 3.}$

Hence, After 3 Hours The Second Car will Overtake the First Car.