TNPSC – PROBABALITY

TNPSC – PROBABALITY

Probabality:

Random experiment:

An experiment is called random experiment if it satisfies the following two conditions:

(i) It has more than one possible outcome.

(ii) It is not possible to predict the outcome in advance.

Sample space:

Consider the experiment of rolling a die. The outcomes of this experiment are 1, 2, 3, 4, 5 or 6.

The set of outcomes {1, 2, 3, 4, 5, 6} is called the sample space of the experiment.

Event:

The set representing the desired outcome of a random experiment is called an event. Event is a subset of the sample space. Consider the experiment of tossing a coin two times. An associated sample space S = {HH, HT, TH, TT}

Now suppose that we are interested in those outcomes which correspond to the occurrence of exactly one head. We find that HT and TH are the only elements of S corresponding to the occurrence of this happening (Event). These two elements form the set E = {HT, TH}.

Defenition of Probabality:

If in an experiment there are “n” occurrences out of which “m” occurrences are favourable to a particular event E, then the probability of the event E is defined as P(E) = m/n.

Probability = Favourable outcomes (m) / Sample Space (n)