Question

For a trip of 800 km, a truck travels the first 300 km at a speed of 50 km/h. At what speed should it cover the remaining distance, so that the average speed is 60 km/hr?

• A. 72 kmph
• B. 600/13 kmph
• C. 52 kmph
• D. 750/11 kmph

Answer 1

Answer:

D. 750/11 kmph

$avarage$ $speed =\frac{"total distance"}{"total time"}$

we have to find the time

300 km with 50kmph

time = 300/50=6hrs

ava speed = 60kmph

$60=\frac{800}{6+x}$

$3=\frac{40}{6+x}$

$18+3x=40$

$3x=40-18=22$

$x=22/3$

the speed of the remaining distance is

$= \frac{500}{22/3}$

$=\frac{1500}{22}=\frac{750}{11}$