Question

A car travel the fist 30km with a uniform speed of 60km H-1 and the next 30km with a uniform speed of 40km h-1 calculator (1) the total time of journey (2) the average speed of the car
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Answer 1

Answer:

The car travels 30 km in the speed of 60 km/hr.

And, then it travels 30 km in the speed of 40 km/hr.

We know, Speed = Distance/Time.

Hence,

Case 1 :

⇒ 60 = 30/Time

⇒ Time = 30/60

⇒ Time = 1/2

⇒ Time = 0.5 hr

Case 2 :

⇒ 40 = 30/Time

⇒ Time = 30/40

⇒ Time = 3/4

⇒ Time = 0.75 hr

Total time of the journey = 0.5 + 0.75 = 1.25 hr

Average speed = (30+30)/1.25 = 60/1.25 = 48 km/hr.

Hence, Total time taken = 1.25 hr and average speed = 48 km/hr.

Answer 2

$\sf✒Here \: we \: Go !!$

Given:

A car travels first 30 km with a speed of 60 km/h and next 30 km with a speed of 40 km/h.

That means,

✒Total Distance = 30 + 30 = 60 km

Time taken to travel first half = Distance covered for the first half / speed of the car

Time taken to travel first half = 30 / 60

→ Time taken to travel first 30 km = (1/2) hours.

✒Similarly,

Time taken to travel next 30 km = 30 / 40

→ Time taken to travel next 30 km = (3/4) hours.

Total Time of the journey = 1/2 + 3/4 = (2 + 3) / 4

• Total Time of the journey = (5/4) hours

✒Average speed of the car = Total Distance travelled / total Time taken.

→ Average speed of the car = 60 / (5/4)

→ Average speed of the car = 60 * (4/5)

→ Average speed of the car = 48 km/h.

$\huge \rm \red{Hence \: we \: Are \: done !!}$