A truck covers 30km at a uniform speed of 30km/h .What should be it's for the next 90km if the average speed for the entire journey is 60km/h.
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A truck covers 30km at a uniform speed of 30km/h .What should be it's for the next 90km if the average speed for the entire journey is 60km/h.
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★ Question
A car covers 30km at a uniform speed of 30km/h . What should be its speed for the next 90 km if the average speed for the entire journey is 60km/h?
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★ Solution
Given: total distance= 120 km
★ Avg. Speed = 60 km/h
★ Time taken by car to cover 30 km= 30/30= 1 hr
★ Let the speed of car for next 90km be x
So,
★ the time taken to complete 90 km = 90/x
Now,
★ Avg. Speed = total distance/ total time taken
→ 60 = 120/(1+(90/x))
→ 60(x+90)= 120x
→ 60x + 5400 = 120x
→ 60x = 5400
→ x = 90 km/h (speed for next 90 km)
Verified answer
Answer:
The speed of the car for next 90 km is 90 km/hr.
Given data:
The speed of car which covers 30 km = 30 km/h
The average speed of the journey = 60 km / hr
To find:
The speed of the car for next 90 km
= ?
Solution:
To find the average speed for the whole journey, we need to find the mean value of the given speed values.
[tex]60 = \frac{30 + x}{2} [/tex]
[tex]30 + x = 120[/tex]
There by,
[tex]x = 120 - 30 = 90[/tex]
Therefore, the speed for the rest of the travel is 90 km/hr.