Question

A car travel 30 kilometre at the speed of 40 kilometre per hour and next 30 kilometre at the speed of 20 kilometre per hour find it average speed

Answer 1

Given :-

• A car travel 30 kilometre at the speed of 40 kilometre per hour and next 30 kilometre at the speed of 20 kilometre per hour.

To find :-

• Average speed

Solution :-

• In first case

A car travel 30 kilometre at the speed of 40 kilometre per hour

• Distance (D1) = 30 km
• Speed = 40km/h

→ Time = Distance/speed

→ t1 = 30/40

→ t1 = 3/4 hrs

• In second case

A car travel 30 kilometre at the speed of 20 kilometre per hour

• Distance (D2) = 30 km
• Speed = 20km/h

→ Time = Distance/time

→ t2 = 30/20

→ t2 = 3/2 hrs

As we know that

→ Average speed = Total distance travelled/total time

→ Average speed = D1 + D2/t1 + t2

→ Average speed = 30 + 30/3/4 + 3/2

→ Average speed = 60/3 + 6/4

→ Average speed = 60/9/4

→ Average speed = 60 × 4/9

→ Average speed = 26.6 km/h

Hence,

• Average speed of car is 26.6km/h

Answer 2

Answer:

total distance=60 km

time is (30/40*60+30/20*60)/60=2.25 hours

average speed=60/2.25=26.66bar km/hr

thank you