A car travels for 6 hours at different speeds. For the first hour, it travels at 60 m/s, for the next 2hours at 50 m/s and for the remaining time at y m/s. If the average speed for the entire journey is 52 m/s, find the value of y.
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Answer:
y = 50⅔ ≈ 50.6667
[ So the speed is 50⅔ m/s = 182.4 km/hr ]
Step-by-step explanation:
Let a be the distance travelled in the first hour.
Let b be the distance travelled in the second hour.
Let c be the distance travelled in the third hour.
Since
- distance = speed × time
the given information says
- a = 60 m/s × 1 hr = 60 m hr/s (a strange unit, but there's no need to convert to m or km since the units don't matter; we just need to always use the same units)
- b = 50 m/s × 2 hr = 100 m hr/s
- c = y m/s × 3 hr = 3y m hr/s
- a + b + c = 52 m/s × 6 hr = 312 m hr/s
This gives
60 + 100 + 3y = 312 ⇒ y = (312 - 160) / 3 = 152 / 3 = 50⅔
Hope this helps.
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