A sales agent travels a distance of 50 km in 2 hours and 30 minutes. How much faster, in kilometers per hour, on average, must he travel to make such a trip in 5/6 hours less time?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 10
Average speed is the distance divided by the time taken. The distance stays 50 km; only the time is cut, so the new speed is found and compared with the present one.
Present time: 2 h 30 min \(=\frac{5}{2}\) h, so present speed \(\displaystyle =\frac{50}{5/2}=20\) km/h
New time: \(\displaystyle \frac{5}{2}-\frac{5}{6}=\frac{15-5}{6}=\frac{5}{3}\) h
New speed \(\displaystyle =\frac{50}{5/3}=30\) km/h
Increase in speed \(=30-20=10\) km/h
Tip: The question asks how much faster, not the new speed; 30 km/h in Option (2) is the new speed itself.