Question

If the speed of a car is increased by 12 km/h, it takes 40 minutes less to cover a
distance of 240 km. Find the original speed of the car.

Answer 1

Answer:

I think ur answer is 20km/hr

Answer 2

Given : the speed of a car is increased by 12 km/h, it takes 40 minutes less to cover a distance of 240 km

To Find :  . Find the original speed of the car.

Solution:

Distance = Speed * Time

original speed of the car  = x  km/hr

Time taken = 240 / x  hr

speed of a car is increased by 12 km/h,

new speed = x + 12 km/hr

Time taken = 240/(x + 12)

Less time taken = 40 mins = 2/3  hr

=> 240/x   - 240/(x + 12)  = 2/3

=>  360 ( 1/x  - 1/(x + 12)  = 1

=> 360 ( x + 12 - x)  = x ( x + 12)

=> 360 * 12  = x²  + 12x

=> x²  + 12x  - 360 * 12 = 0

=> x²  +  72x - 60x  - 360 * 12 = 0

=> x(x + 72) - 60(x + 72) = 0

=> x = 60

Hence   the original speed of the car. = 60 km/hr

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