1.

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.​

Answer»

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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