Average Speed Examples Time and Distance

In this class, We discuss Average Speed Examples Time and Distance.

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Example 1:

A man traveled from the village to the post office at 25 kmph. And travel back at the rate of 4 kmph.

Suppose the whole journey takes 5 hr 48 min. Find the distance of the post office from the village?

Solution:

The diagram below explains why we need to use average speed.

Given Time in the question. To find the distance, we find the average speed?

In this example, we use the average speed formula if the same distance traveled.

speed = 2xy/(x+y)

s = 2 * 25 * 4/(25 + 4)

s = 200/29 kmph.

Time = 5 hr 48 min.

Time = 5 4/5 hr

Distance = x

Traveled two times so distance = 2x

2x = 200/29 * (29/5)

2x = 40

x = 20

Example 2:

An airplane flies along the four sides of the square at a speed of 200, 400, 600, and 800 Km/hr.

Find the average speed?

Solution:

Average speed = Total distance / Total Time.

Square side = x

speed = distance/time.

time = distance / speed

t1 = x/200

t2 = x/400

t3 = x/600

t4 = x/800

Average speed = 4x / (x/200) + (x/400) + (x/600) + (x/800)

Average speed = 384 kmph

Example 3:

A car travels the first one-third of the distance at a speed of 10 kmph

The next one-third of the distance at a speed of 20 kmph.

The last one-third of the distance at a speed of 80 kmph.

Find the average speed?

Solution:

Average speed = Total distance / Total Time.

Assume distance = x

Time = distance/speed

t1 = (x/3)/10 = x/30

t2 = (x/3)/20 = x/60

t3 = (x/3)/60 = x/180

Average speed = x/ (x/30) + (x/60) + x(180)

Average speed = 18 kmph