Question

A car covers 40% of a certain distance at a pace of 20 km/h and the remaining distance at a pace of 30 km/h. What is the average speed of the car for the entire journey?

• A. 24 km/h
• B. 25 km/h
• C. 26 km/h
• D. 27 km/h

Answer 1

Answer:

B. 25 km/h

Assume the total distance is (100) km.

First part

(40%) of distance (= 40) km at (20) km/h

Time taken:

$\frac{40}{20}=2 \text{ hours}$

Second part

Remaining distance (= 60) km at (30) km/h

Time taken:

$\frac{60}{30}=2 \text{ hours}$

Total distance and time

• Total distance (=100) km

• Total time (=2+2=4) hours

Average speed:

$\frac{100}{4}=25 \text{ km/h}$

So, the average speed is:

$\boxed{25 \text{ km/h}}$