A student covers a distance by cycle at 6km/h. He returns to the starting point in a bus at a speed of 42km/h. The average speed (in km/h) for the entire journey is:
- A12.75
- B24
- C10.25
- D10.5
Solution & Step-by-step Explanation
When a person travels equal distances at two different speeds, say v
1
and v
2
, the average speed for the entire journey is given by the formula:
Average Speed=
v
1
+v
2
2⋅v
1
⋅v
2
Given:
v
1
=6km/h
v
2
=42km/h
Substitute these values into the formula:
Average Speed=
6+42
2×6×42
=
48
504
=10.5km/h
1
and v
2
, the average speed for the entire journey is given by the formula:
Average Speed=
v
1
+v
2
2⋅v
1
⋅v
2
Given:
v
1
=6km/h
v
2
=42km/h
Substitute these values into the formula:
Average Speed=
6+42
2×6×42
=
48
504
=10.5km/h