Question

A covers a certain distance with car average speed of 20 km/hr and reach his destination in 6 hours, While B covers the same distance in 3 hours. If A increases his average speed by 25% and B decreases his average speed by 10 km/hr. What would be the difference between in their time taken to reach the destination?
1. 54 min
2. 1 hour
3. 48 min
4. 45 min
5. 35 min

Answer 1

Correct Answer - Option 3 : 48 min

Given:

The average speed of A is 20 km/hr.

The time taken to cover a distance by A is 6 hours.

The time taken to cover a same distance by B is 3 hours.

Formula Used:

Distance = Speed × Time

Calculation:

The distance cover by A = 20 × 6 = 120 km

The speed of B = 120/3 = 40 km/hr

According to the question;

The new speed of A = (100 + 25)/100 × 20 = 25 km/hr

The new speed of B = 40 - 10 = 30 km/hr

Then, Time taken by A to cover the distance = 120/25 = 24/5 hours

Time taken by B to cover the distance = 120/30 = 4 hours

The difference between the time taken by A and B = 24/5 - 4  = 4/5 hour = 4/5 × 60 = 48 min

∴ The difference between the time taken by A and B is 48 min.