During flight there are two instants of time when the projectile is at same height from the ground. Show that the sum of the two instants is equal to total time of flight.

Projectile is fired horizontally from the top of a tower of height h. Calculate time of descent

Find the sum of the product of 1,2,3….20 taken two at a time.

A stone thrown at an angle theta to the horizontal reaches a maximum height h . The time of flight of the stone is

Two dice are tossed 6 times. Find the probability that 7 will show an exactly four of the tosses.

If then sum of two positive numbers in constant then show that their product is maximum when they are equal.

A stone dropped from the top of a tower of travel 5/9th of the height of the tower during the last second of its fall . The time of fall is.

There are three coins. One is a two tailed coin (having tail on both faces) another is a biased coin that comes up heads 60% of the times and third is an unbiased coln. One of the three coins is chosen at random and tossed and it shows tail. What is the probability that it is a two tailed coin.