Question

A girl walking at a speed of 20 km/hr reaches her college 45 min late. Next time, she increases her speed by 5 km/hr but still she is late by 30 min. What is the distance between college and her home?

1. 20 km
2. 50 km
3. 25 km
4. 40 km
5. None of these

Answer 1

Correct Answer - Option 3 : 25 km

Given:

Reaches 45 min late when walking at speed of 20 km/h

Reaches 30 min late when walking at speed of 25 km/h

Concept:

Speed = Distance/Time

Calculation:

Let, the distance of college from her home be x km

Difference b/w the time = (45 ─ 30) min = 15/60 = (1/4) hr

New speed after increasing her speed during the journey = (20 + 5) km/hr = 25 km/hr

According to the question,

⇒ (x/20) - (x/25) = 1/4

⇒ (5x - 4x)/100 = 1/4

⇒ x/100 = 1/4

⇒ x = 100/4

⇒ x = 25

∴ Total distance is 25 km.