Question

A boy covers a distance of 20 km in 2½ hours, partly on foot at the rate

of 5 km/hour and partly on bicycle at the rate of 10 km/hour. Find the
distance covered on foot.

Answer 1

Given:

Total Distance = 20 km

Total time taken = 5 km

Speed on foot = 5 km/h

Speed of bicycle = 10 km/h

To Find:

The distance on foot

Solution:

Define the variable:

Let the distance traveled on foot be x

Distance traveled by bicycle = 20 - x

Find the time taken to travel on foot:

Time = Distance ÷ Speed

Time = x/5 hour

Find the time taken to travel by bicycle:

Time = Distance ÷ Speed

Time = (20 - x)/10 hour

Given that the total time taken is 2.5 hour:

x/5 + (20 - x)/10 = 2.5

2x + (20 - x) = 25

2x + 20 - x = 25

x + 20 = 25

x = 5 km

Distance traveled on foot = 5 km

Answer 2

5km

Explanation:

Boy cover distance in 2 1/2 hours

he covers by foot = 5km/hr

In 1 hour he complete 5km

he covers distance by bicycle = 10km /hr

In 1 hour he complete = 10 km

total distance 20 km

x/5 + (20-x ) /10 = 5/2

x +20 =25

x = 25-20

x = 5