A box contains 6 bottles of 1 drink, 3 bottles of variety 2 drink and 4 bottles of variety 3 drinks. Three bottles of them are drawn at random, what is the probability that the three are not of the same variety.

A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the second and third pipe can fill a tank together?

$if \frac{x^{24}+1}{x^{12}}=7$ then the value of $\frac{x^{72}+1}{x^{36}}$ =?

There is a tree between houses of A and B. If the tree leans on A's house, the tree top rests on his window which is 12m from ground. If the tree leans of B's house, the tree top rests on his window which is 9m from ground. If the height of the tree is 15m, what is distance between A's and B's house?

A landscape architect is designing a rectangular flowerbed to be border with 28 plants that are placed 1m apart. He needs an inner rectangular space in the center of plants that must be 1m from the border of the bed and that require 24 square meter for planting. What should the Overall dimensions of the flowerbed be?