A car covers a certain distance at a speed of 45 km/h and returns to the starting point following the same path at a speed of 36 km/h. Find the average speed for the entire journey (in km/h).
- AOption (a)
40
- BOption (b)
38
- COption (c)
42
- DOption (d)
35
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Correct answer
40
Why this answer is correct
Given:
Speed at the time of going = 45 km/h
Speed at the time of return to the starting point = 36 km/h.
Concept used:
When distance is constant then,
Average speed = (2xy)/(x + y)
Here,
x = Speed at time of going
y = speed at the time of returning
Calculation:
Average speed = (2 × 45 × 36)/(45 + 36) km/hr.
⇒ (2 × 45 × 36)/81 km/hr.
⇒ (3240)/81 km/hr.
⇒ 40 km/hr.
∴ The average speed for the entire journey (in km/h) is 40.
