A boat covers 143 km upstream in 13 hours and the same distance downstream in 11 hours. What is the speed (in km / hr ) of the boat in still (without stream) water?

A student walks from his house at a speed of K per hour and reaches his school 6 minutes late. The next day he...

A man buys an article for 10% less than its value and sells it for 10% more than its value. His gain or loss p...

A reservoir has two pipes, A and B. A can fill the reservoir 5 hours faster than B. If both together fill the...

What is the average of odd numbers from 1 to 40?

How many different numbers of two digits can be formed with the digits 1, 2, 3, 4, 5, 6; no digit being repeat...

If the area of a triangle with base x is equal to the area of a square with side x, then the altitude of the t...