Question

Q 28 A train travels first 800 kms at an
average rate of 180 kmph and further
travels the same distance at an average
rate of 120 kmph. Determine the average
speed of the train over the whole
journey.
Ops: A 164 kmph
B.
c
100 kmph
140 kmph
160 kmph
0.​

Answer 1

Answer:

144 kmph

Step-by-step explanation:

Time taken for first 800 kms = $\frac{Distance}{Speed}$ = $\frac{800}{180} hours= \frac{40}{9} hours$

Time taken for next 800 kms = $\frac{Distance}{Speed}$ = $\frac{800}{120} hours= \frac{20}{3} hours$

Total Distance covered = 800 kms + 800 kms = 1600 kms

Total Time Taken = $\frac{20}{3} + \frac{40}{9} = \frac{60+40}{9} = \frac{100}{9}$ hours

Average Speed = $\frac{Total Distance}{Total Time} = \frac{1600}{\frac{100}{9} } = 16 * 9 = 144 kmph$