Question

Two places A and B are 80 km apart. Two persons start from A at the same time and meet 15 km before B. If the difference between their speeds is 36 km/h, then find the speed of the slower one.   
1. 65 km/h
2. 95 km/h
3. 72 km/h
4. 78 km/h

Answer 1

Correct Answer - Option 4 : 78 km/h

Given:

Distance = 80 km

Meet 15 km before B

Difference in speeds = 36 km/h

Concept:

For the same amount of time, the ratio of distance traveled is directly proportional to the ratio of speeds.

Calculation:

Distance traveled by the faster one = 80 + 15 = 95 km

Distance traveled by the slower one = 80 - 15 = 65 km

Distance ratio = 19 : 13

So, Speed ratio = 19 : 13

Difference = 19 - 13 = 6 ratio

A.T.Q

6 ratio = 36 km/h

13 ratio = 36/6 × 13 = 78 km/h

∴ The speed is 78 km/h