Question

A train travels the first 160 km at 64 km/hr and the next 160 km at 80 km/hr. What is the average speed of the train?

• A. 67.55 km/hr
• B. 71.11 km/hr
• C. 73.89 km/hr
• D. 69.38 km/hr

Answer 1

Answer: (B)

71.11 km/hr

Answer 2

Speed for first$160 km$=$64 km/hr$
Speed for next$160 km$=$80 km/hr$
Time taken for first$160 km$=$\frac{160}{64}$=$2.5 hours$
Time taken for next&$160 km$=$\frac{160}{80}$=$2 hours$
Total time taken =$(2.5+ 2) hours = 4.5 hours$
Total distance =&$(160+160) = 320 km$
$Average speed =\frac{Total distance}{Time taken}$
$Average speed = \frac{320}{4.5}$=$71.11 km/hr$
$\therefore \text{The average speed is } 71.11 km/hr$
The correct answer is (B): 71.11 km/hr;