Correct Answer - Option 3 : 15 hrs

**Given:**

Speed of Karnataka Express = 80 km/h

Speed of Rajdhani express = 120 km/h

Distance between Delhi to Bangalore = 3,000 km

**Concept used:**

When two objects move in the opposite direction, then

Relative speed = S_{1 }+ S_{2}

where S_{1} and S_{2 }= Speed of trains

Formula used:

Speed = Distance/Time

**Calculation:**

According to the questions,

The relative speed of both trains in opposite directions = 80 + 120

⇒ 200 km/h

Time required to meet the train = Distance/Speed

⇒ 3000/200

⇒ 15 hours

**∴ The required time is 15 hours.**