Question 53

A truck covers a distance of 384 km at a certain speed. If the speed is decreased by 16 km/h. it will take 2 hours more to cover the same distance. 75% of its original speed (in km/h) is:

Solution

Let the speed be s km/hr.

$$\frac{384}{s-16}$$ - $$\frac{384}{s}$$ = 2

384 {$$\frac{1}{s-16}$$ - $$\frac{1}{s}$$} = 2

384 $$\times$$ 8 = s$$^2$$ - 16s

s$$^2$$ - 16s - 3072 = 0

s = 64 km/hr

75% of its original speed (in km/h) is: $$\frac{75}{100}$$ $$\times$$ 64 = 48 km/hr

So, the answer would be 48 km/hr.

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