Correct Answer - Option 4 : 80 km
Given:
Time taken to cover distance between P and Q = 7 hours
Speed for (1/4)th of the distance = 10 km/hr
Speed for remaining distance = 12 km/hr
Formula used:
Time = Distance/Speed
Calculation:
Let distance be 4x km
According to question,
⇒ (x/10) + (3x/12) = 7
⇒ 21x/60 = 7
⇒ x = 20
Total distance = 4x = 4 × 20 = 80 km
∴ The total distance between P and Q is 80 km