Q.A box contains 75 tickets numbered 1 to 75. A ticket is drawn at random from the box. Find the probability that, a) Number on the ticket is divisible by 6 b) Number on the ticket is a perfect square c) Number on the ticket is prime d) Number on the ticket is divisible by 3 and 5.

For a random experiment whose outcomes are all equally likely (no outcome is preferred over any other), the classical definition assigns to an event $A$ the probability $P(A)=n(A)/n(S)$, the fraction of all outcomes that are favourable to $A$. This single ratio - favourable outcomes over total outcomes - is the computational engine of the whole chapter: once a sample space is built and the outcomes favouring an ev …