Question

7
A car covers a distance of 400 km at a certain speed. Had the speed been 12 km/h
more, the time taken for the journey would have been 1 hour 40 minutes less. Pind
the original speed of the car.
(2012
d distance of 400 km at an average speed of % km/​

Answer 1

Step-by-step explanation:

let original speed of car is x km/and

Increased speed of car be x+12 km/h

Now take

T1 be the time require to cover 400 km = 400/x

T2 be the time require to cover 400 km when speed increased = 400/x+12

Now, as given time taken for cover 400 km would have 1 hr 40 min. less

therefore,

T1 - T2 = 1(40/60)

= 5/3

400/x - 400/x+12 = 5/3

400(1/x - 1/x+12) = 5/3

400(12/x(x+12) = 5/3

12/x(x+12) = 5/3 x 400

x^2 + 12x - 2880 = 0