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

The Correct Option is B

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;