Question

A car moves with the speed of 30 km/h for half an hour , 25 km /h for one hour and 40 km/h for two hours . Calculate its average speed .

Answer 1

Hi there! Here is your answer:
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Let us find the distances first.

□ Car moves with 30 kmph for half an hour. This means 30 x 1/2 = 15 km

□ Car moves with 25 kmph for an hour. This means 25 x 1= 25 km

□ Car moves with 40 kmph for half an hour. This means 40 x 2 = 80 km

So, the total distance is 80 + 25 + 15 = 120

On, adding the hours, we have: 0.5 + 1 + 2 = 3.5 hours

□ Now we know that, S = D / T

Therefore, S = 120 / 3.5

Ans. 34.2 kmh is the average speed of the car.
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I hope this helps!

Answer 2

speed=30km/h

time=0.5hrs

distance=s*t

=15km

speed=25km/h

time=1hrs

distance=s*t

=25km

speed=40km/h

time=2hrs

distance=s*t

=80km

average speed= total distance/total  

time taken

= (15+25+80)/(1+2+0.5)

= 120/3.5

= 34.28km/h.