In a precision bombing attack, there is a `50%` chance that any one bomb will strick the target. Two direct hits are required to destroy the target completely. The number of bombs which should be dropped to give a `99%` chance or better of completely destroying the target can be

The probability of a bomb hitting a bridge is (2)/(3) . Two direct hits are needed to destroy the bridge. The minimum number of bombs required such that the probability of bridge being destroyed is greater than (3)/(4) , is

The probability of a bomb hitting a bridge is 1/2 and two direct hits are needed to destroy it. The least number of bombs required so that the probability of the bridge being destroyed is greater 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.]

At the height 80 m , an aeroplane is moving with 150 m//s . A bomb is dropped from it so as to hit a target. At what distance from the target should the bomb be dropped (given g = 10 m//s )

A rifleman is firing at a distance target and hence has only 10% chance of hitting it. Find the number of rounds; he must fire in order to have more than 50% chance of hitting it at least once.

Molecules of the amino acids that comprise our proteins have the property of being non-super imposable on their mirror images because,. They are said to be chiral or possess 'handedness'. Most of the amino acids are of left handed form, but with no reasons available. Even more interesting recent experiments have shown that a 7-9% excess of four amino acids is present in Murchison meteorite discovered in 1970. This analysis shows life could arise outside the confines of earth. The origin of unequal distribution is probably because of electromagnetic radiations emitted in a corkscrew fashion from the poles of spinning neutron stars could lead to a bias of one mirror image isomer over another when molecules form in interstellar space. A stereogenic carbon can be defined as a carbon atom bearing groups of such nature that an interchange of any two groups will produce a stereoisomer. The device that is used for measuring the effect of optically active compounds on plane polarized light is a polarimeter. The analyser in the polarimeter decides the activity of compound present. This is being decided on the basis of angle by which axis of analyser has to be rotated for complete brightness. Left, right or no adjustment decides l, d - activity or optical inactivity respectively. Optically inactive isomer possessing chiral centres are categorized as

A man firing a distant target has 20% chance of hitting the target in one shot. If P be the probability of hitting the target in atmost 'n' attempts where 20P^(2)-13P+2 le0 . then maximum value of n is.

A man firing a distant target has 20% chance of hitting the target in one shot. If P be the probability of hitting the target in atmost 'n' attempts where 20P^(2)-13P+2 le0 . then maximum value of n is.