Question

is
3. A bus covers a distance of 90 km at a uniform speed. Had the speed been 15 km/hour
more it would have taken 30 minutes less for the journey. Find the original speed of
the bus.
​

Answer 1

Answer:

Original Speed = 45 Km/h

Step-by-step explanation:

Let the uniform speed be x km/h.

Time taken in first case = 90/x                                  - (1)

Time taken in second case = 90/(x+15)                    - (2)

Now,

90/x = 90/(x+15) + 1/2

90/x - 90/(x+15) = 1/2

1350/(x^2+15x) = 1/2

2700 = x^2 +15x

x^2 + 15x - 2700 = 0

x^2 + 60x - 45x - 2700 = 0

(x + 60)(x - 45) = 0

x = -60(Not Possible)                          OR                                   x = 45

This implies-

Original speed = 45 km/h