The speeds of two running trains are in the ratio 7 : 9. Moving along parallel tracks in opposite directions, they take 4 seconds each to cross a telegraph post. Find the time taken by them to cross each other completely. MCQ with Answer and Explanation
The speeds of two running trains are in the ratio 7 : 9. Moving along parallel tracks in opposite directions, they take 4 seconds each to cross a telegraph post. Find the time taken by them to cross each other completely.
A. 5 seconds
B. 3.5 seconds
C. 4.5 seconds
D. 4 seconds
Answer: Option D
Solution (By JKSSB Mock Tests)
Let the speeds be 7x and 9x. Length of first train = 7x * 4 = 28x. Length of second train = 9x * 4 = 36x. Total distance to cross each other = 28x + 36x = 64x. Relative speed in opposite directions = 7x + 9x = 16x. Time taken = 64x / 16x = 4 seconds.
A person can row 8 km/h in still water. If the river current flows at 4 km/h, it takes him 4 hours to row to an outpost and back. Find the distance of the outpost.
A delivery coach covers a highway stretch at 40 km/h. If the driver spikes the speed index to 60 km/h, the coach lands at the station terminal 15 minutes early. Find the track sector distance.
Explanation:
Time difference = 15 minutes = 15/60 = 1/4 hours. Let distance be d. d / 40 - d / 60 = 1/4 => (3d - 2d) / 120 = 1/4 => d / 120 = 1/4 => d = 30 km.
No comments yet. Be the first to start the discussion!