Question

A boy boarded a train on 28th June 2021 at Madgaon for Nagarcoil. The train departed at 22:30 hours from Nagarcoil and reached Madgaon at 04:30 hours on 30th June 2021. If the distance covered by the train during this time interval is 2640 km, the average speed of the train was
1. 80 km/hr
2. 85 km/hr
3. 88 ​km/hr
4. 86 ​km/hr

Answer 1

Correct Answer - Option 3 : 88 ​km/hr

Concept:

• Speed: The distance travelled by the body in unit time.
• \(Speed = \frac{{Distance}}{{Time}}\)
• Also, \(Time= \frac{{Distance}}{{Speed}}\)
• Average Speed: Since the body does not always have the same speed, So we use the concept of average speed. It is the ratio of total distance covered to total time taken by the body.
• \(Average\;Speed = \frac{{Total\;Distance}}{{Total\;Time}}\)

Calculation:

Station	Date	Arrival	Departure
Madgaon	28th June 21	-	22:30
Nagarcoil	30th June, 21	04:30	-

 

Total distance = 2640 km

Total time taken = 1.5 hr + 24 hr + 4.5 hr = 30 hr

We know that,

\(Average\;Speed = \frac{{Total\;Distance}}{{Total\;Time}}\)

\(⇒ Average\;Speed = \frac{{2640\;km}}{{30\;hr}}\)

⇒ Average Speed = 88 km/hr

The average speed of the train was 88 km/hr