Question

a car moves with a speed of 30 km per hour for half an hour 25 km per hour for one hour and 40 km per hour for 2 hour. calculate the average speed of the car.

Answer 1

speed = 30km/h
time = 1/2h
distance = 30 * 1/2 = 15km

speed = 25km/h
t = 1h
distance = 25 * 1 = 25km

speed = 40km/h
t = 2h
distance = 40 * 2 = 80km

total distance = 15 + 25 + 80 = 120km
total time = 3.5h
avg speed = 120/3.5 = 34.29km/h(approx)

Answer 2

Hii..
Here is your answer..

Solution:-
Distance travelled in half an hours=
$= > 30 \times \frac{1}{2} \\ = > 15km$
Distance travelled in the 1 hrs at speed of 25km/h=
$= > 25 \times 1 \\ = > 25km$
Distance travelled in 2 hrs at speed of 40km/h
$= > 40 \times 2 \\ = > 80km$
Now,
Total time =
$= > \frac{1}{2} + 1 + 2 \\ = > \frac{7}{2} \\ = > 3hrs \: 30min$
Total distance travelled=15+25+80
$= > 120km$
Since,
$average \: speed = \frac{total \: distance}{total \: time} \\ = > \frac{120}{ \frac{7}{2} }$
$= > \frac{120 \times 2}{7}$
$= > \frac{240}{7} \\ = > 34.28$
Hence,
Average speed =34.28km/h

Hope it helps uh...✌️✌️✌️