Question

A cyclist travels 15 km at 5 km/h and then further 40 km at 20 km/h. What is his average speed of the journey?

• A. 11 km/hr
• B. 12 km/hr
• C. 15 km/hr
• D. 20 km/hr

Answer 1

The correct option is A 11 km/hr

Time taken = $\frac{Distance}{Speed}$

Ist leg of the journey: Distance = 15 km, Speed = 5 km/h

Time taken to cover the 1st leg of the journey = $\frac{15}{5}$ = 3 hours

2nd leg of the journey: Distance = 40 km, speed = 20 km/h

Time taken to cover the 2nd leg of the journey = $\frac{40}{20}$ = 2 hours

Time taken to cover the entire journey = 3 + 2 = 5 hours

Average speed for the whole journey = $\frac{Totaldistancetravelled}{Totaltimetaken}$

= $\frac{15+40}{5}$ = $\frac{55}{5}$ = 11 km/h