Reshma covers 45 km at a speed of 15 km/h by bicycle, 80 km at a speed of 40 km/h by car, and another 6 km at a speed of 2 km/h on foot. Find her average speed for the whole journey (correct to 2 decimal places).
- A18.36 km/h
- B43.50 km/h
- C16.38 km/h
- D15.25 km/h
Solution & Step-by-step Explanation
Average speed is calculated as the total distance covered divided by the total time taken.
Average Speed=
Total Time
Total Distance
Total Distance:
Total Distance=45+80+6=131km
Total Time:
Time taken by bicycle (t
1
) =
15
45
=3hours
Time taken by car (t
2
) =
40
80
=2hours
Time taken on foot (t
3
) =
2
6
=3hours
Total Time=3+2+3=8hours
Average Speed:
Average Speed=
8
131
=16.375km/h
Rounding off to 2 decimal places gives 16.38km/h.
Average Speed=
Total Time
Total Distance
Total Distance:
Total Distance=45+80+6=131km
Total Time:
Time taken by bicycle (t
1
) =
15
45
=3hours
Time taken by car (t
2
) =
40
80
=2hours
Time taken on foot (t
3
) =
2
6
=3hours
Total Time=3+2+3=8hours
Average Speed:
Average Speed=
8
131
=16.375km/h
Rounding off to 2 decimal places gives 16.38km/h.