Question

If the speed of a car is decreased by 8km/hr .it takes 1 hour more to cover a distance of 240km find the original speed of the car.

Answer 1

Answer:

• Time = 1 hr
• Distance = 240 km
• Decreased speed = (x - 8) km/hr

Let the original speed be x km/hr.

❍ According to Question now,

→ Time = Distance/Time

→ 1 = 240/(x - 8) - 240/x

→ 1 = 240x - 240(x - 8)/x(x - 8)

→ 1 = 246 x - 246x + 1920/x² - 8x

→ x² - 8x = 1920

→ x² - 8x - 1920 = 0

By splitting middle term we get :

→ x² - 40x + 48x - 1920 = 0

→ x² - 48x + 40x - 1920 = 0

→ x(x - 48) + 40(x - 48) = 0

→ (x + 40) (x - 48) = 0

→ x = -40 or x = 48

• The speed is never negative so it is not a required solution.

Therefore, Original Speed x is 48 km/hr.