8 clay targets are arranged as shown. If N be the number of different way they can be shot (one at time) if no target can be shot until the target(s) below it have been shot. Find the ten's digit of N.

The adjoining diagram shows 8 clay targets, arranged in 3 columns to be shot by 8 bullets. The number of ways in which they can be shot such that no target is shot before all the targets below it,if any,are first shot is (A) 560 (B) 72 (C) 40320 (D) none of these

Ten different books are arranged on a shelf . Find the number of different ways in which this can be done. If two specified book are (a) to be together, (b) not to be together.

Find the number of ways in which n different beads can be arranged to form a necklace.

What is the number of ways in which n different objects can be arranges at a round table ?

A can hit a target 3 times in 6 shots, B 2 times in 6 shots and C 4 times in 4 shots .What is the probability that at least two shots hit the target.

A can hit a target in 3 out of 4 shots and B can hit the target in 4 out of 5 shots. What is the probability of hitting the target ?

A can hit a target 4 times in 5 shots.B three times in 4 shots,C two times in three shots.Calculate the probability that any two will hit the target.

A man can hit a target 2 times out of every 3 shots. The least number of times he must shoot, so that the probability of hitting the target at least twice is more than 0.9 is

In a shooting competition, three targets are set as shown: Target (I) has four rings on which a person can hit in order from inside to outside. Target (II) has three rings on which a person can hit in order from outside to inside. Target (III) has five rings on which a person can hit in order from inside to outside. The number of ways in which 12 shots (one at each ring) can be made: [Hint: Any target can be chosen before not completing specific target but order of hit for a particular target should be as specified above in condition.]