Question

Nagarjun was travelling on one side of the outer ring road with a constant speed of 105 km/h in his car. Chaitanya was travelling with a constant speed of 75 km/h in the opposite direction. When they crossed each other, Nagarjun decided to take a U-turn and meet him. But before taking a U turn, Nagarjun had to travel for another 5 minutes. How long will it take for Nagarjun to meet Chaitanya? [Assume time taken by Nagarjun to take U turn is negligible]
1. 30 min
2. 35 min
3. 25 min
4. 40 min

Answer 1

Correct Answer - Option 2 : 35 min

Let R₁ and R₂ be the relative speeds of Nagarjun with respect to Chaitanya, when they cross each other and when they move in the same direction, respectively.

So, R₁ = 105 + 75 = 180 km/h and R₂ = 105 – 75 = 30 km/h

Distance b/w Nagarjun and Chaitanya just before Nagarjun takes U-turn

= R₁ × 5/60 = 180 × 1/12 = 15 km

Now, time taken by Nagarjun to meet Chaitanya after taking U-turn

= 15/R₂ = 15/30 = 0.5 h = 30 min

Thus, total time required = 30 + 5 = 35 min