Question

a car cover 30km distance at 60km/hr then it cover 90km at the rate of 30km/hr what is the average speed of the car​

Answer 1

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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)

Answer 2

Answer:

The average speed of the car is 240/7 kmph

Explanation:

Given :

A car cover 30 km distance at 60 km/hr, then it covers 90 km at the rate of 30 km/hr

To find :

the average speed of the car

Solution :

we know,

speed = distance covered/time taken

⇒ time taken = distance covered/speed

Time taken to cover 30 km :

distance covered = 30 km

speed = 60 km/hr

time taken = 30/60 = 1/2 hr = 0.5 hr

Time taken to cover 90 km :

distance covered = 90 km

speed = 30 km/hr

time taken = 90/30 = 3 hr

Average speed = total distance covered/total time taken

  = (30 km + 90 km)/(0.5 hr + 3 hr)

  = 120 km/3.5 hr

  = 1200/35 km/hr

  = 240/7 km/hr