Tag: math & puzzles

A boat travels 20 kms upstream in 6 hrs and 18 kms downstream in 4 hrs.Find the speed of the boat in still water and the speed of the water current?

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member ?

Ronald and Michelle have two children. The probability that the first child is a girl, is 50%. The probability that the second child is a girl, is also 50%. Ronald and Michelle tell you that they have a daughter. What is the probability that their other child is also a girl?

A cyclist drove one kilometer, with the wind in his back, in three minutes and drove the same way back, against the wind in four minutes.If we assume that the cyclist always puts constant force on the pedals, how much time would it take him to drive one kilometer without wind?

You walk upwards on an escalator, with a speed of 1 step per second.After 50 steps you are at the end.You turn around and run downwards with a speed of 5 steps per second.After 125 steps you are back at the beginning of the escalator.How many steps do you need if the escalator stands still?

You walk upwards on an escalator, with a speed of 1 step per second.After 50 steps you are at the end.You turn around and run downwards with a speed of 5 steps per second.After 125 steps you are back at the beginning of the escalator.How many steps do you need if the escalator stands still?

A cyclist drove one kilometer, with the wind in his back, in three minutes and drove the same way back, against the wind in four minutes.If we assume that the cyclist always puts constant force on the pedals, how much time would it take him to drive one kilometer without wind?