Question

If the speed of a car is decreased by 8 kilometre per hour it takes 1 hour more to cover a distance of 240 kilometre find the original speed of the car

Answer 1

Answer:

Step-by-step explanation:

Original speed = x km/hr

Distance = 240 km

Speed = distance/time

time (T1) = distance/speed

T1 = 240/x

New speed = x - 8 km/hr

Distance = 240 km

T2 = 240/x - 8

T2 - T1 = 1

240/(x - 8) - 240 / x = 1

240(x) - 240(x-8) / x(x-8) = 1

240x - 240x +1920 / x^2 - 8x = 1

1920 = x^2 - 8x

x^2 - 8x  - 1920 = 0

x(x-48) + 40(x-48) = 0

(x+40)(x-48) = 0

x = -40km/hr or x = 48 km/hr

Speed cannot be negative

Therefore original speed of the car is 48 km/hr