Question

A car moves with a apeed of 30km/h-1 for half an hour , 25km/h-1 for one hour and 40km/h-1 for two hours . Calculate the average speed of car .

Answer me if you can ​

Answer 1

Direct Answer:

34.28 km/h

Given:

★ A car moves with a speed of 30 km/h for half an hour.

★ Then it travels at a speed of 25 km/h for an hour.

★ At last, the car travels at 40 km/h for two hours.

To Find:

the average speed of the car.

Solution:

The average speed of the car would be the total distance travelled divided by the total time taken. So, in order to calculate it, we must find the distance covered by the car in each case.

Case 1:

Car moves at the speed of 30 km/h for half an hour.

We know that:

$\sf{\longrightarrow\:Distance=Speed\times\:Time}$

$\sf{\longrightarrow\:Distance=30\times\dfrac{1}{2}}$

$\sf{\longrightarrow\:Distance=15\:km}$

Case 2:

Car moves at the speed of 25 km/h for an hour.

$\sf{\longrightarrow\:Distance=Speed\times\:Time}$

$\sf{\longrightarrow\:Distance=25\times1}$

$\sf{\longrightarrow\:Distance=25\:km}$

Case 3:

Car moves at the speed of 40 km/h for two hours.

$\sf{\longrightarrow\:Distance=Speed\times\:Time}$

$\sf{\longrightarrow\:Distance=40\times2}$

$\sf{\longrightarrow\:Distance=80\:km}$

Now, we have to calculate the total distance and the total duration of the journey.

Total distance:

$\sf{\longrightarrow\:Total\:distance=15+25+80}$

$\sf{\longrightarrow\:Total\:distance=120\:km}$

Total time taken:

$\sf{\longrightarrow\:Total\:time=0.5+1+2}$

$\sf{\longrightarrow\:Total\:time=3.5\:hours}$

We know that:

$\sf{\longrightarrow\:Average\:speed=\dfrac{Total\:distance}{Total\:time}}$

$\sf{\longrightarrow\:Average\:speed=\dfrac{120}{3.5}}$

$\sf{\longrightarrow\:Average\:speed=34.28km/h}$

Therefore the average speed of the car is 34.28 km/h.