self Maths Puzzle

Q. A man sitting in a train which is travelling at 50 kmph observes that a goods train, travelling in opposite direction, takes 9 seconds to pass him. If the goods train is 280 m long, find its speed.

Read Solution (Total 2)

62 kmph
If speed of goods train=x kmph, relative speed=(50+x)
0.28/(50+x)=9/3600
x=62
11 years agoHelpfull: Yes(1) No(0)

(50+x)*5/18*9=280
or x=62m/sec (ans)
11 years agoHelpfull: Yes(0) No(0)

self Other Question

Q. There are n black balls in box1 and n white balls in box2. A single operation involves transferring a ball from box1 to box2 and a ball from box2 to box1 .what is the probability that box1 has more black balls than white balls at the end of 3 operations? Q. A train 150 m long is running with a speed of 68 kmph. In what time will it pass a man who is running at 8 kmph in the same direction in which the train is going?