Two gun were fired from the same place at an interval of 13 min. A person in a train approaching the place hears the 2nd report 12 min 30 sec later than 1st. Find the speed of the train (in km/hr), supposing that sound travels at 375 m/sec.
Answer & explanation
Correct answer: option 1
(Distance covered by bullet in 30 seconds is equal to the distance covered by train in 12 mins 30 seconds)
Train : Sound
Time 12 min 30 sec : 30 sec
750 : 30
25 : 1
Speed 1 : 25
↓ ↓
×15 ×15
↓ ↓
15m/sec 375
Speed of train = 15m/sec = 15 × \(\frac{18}{5}\) = 54 km/h