A car travels the first 40 km at a speed of 30 km/h, the next 60 km are covered at 36km/h and the final 80 km at 40 km/h. What is the average speed attained by the car over the entire journey?
Answers
average speed = distance travelled /time taken
we know here speed and distance is given only so to find average speed we need to find its time
speed=ditance/time
30=40/t
t=40/30=1.33hr
similarly
36=60/t
t=60/36=1.66hr
and
40=80/t
t=80/40=2hr
now add distance travelled and time taken and divide them
40+60+80=180km
time=1.33+1.66+2=4.99hr
average speed = 180/4.99=36.07km/hr
Answer:
Explanation:average speed = total distance ÷total time
Total distance=40+60+80
Total time=?
We need to find the time.
Let us come from first.
1) distance traveled=40km
Speed=30km\h
Therefore, time =distance \speed
Time=40km\30km.h'-1
Time=1.3333h
Do the same with 2 and 3rd
You will get 2)= 1.66666h
3)=2h
Now, to find average speed we must divide total distance covered by total time taken.
Total distance covered=40+60+80=180km
Total time taken=1.3333+1.6666+2=approximately 4.99 or 5h
Hence average speed=180\4.99=36 or 39.07 km per hour