PROBABILTY

In our daily life, we often used phrases such as 'It may rain today', or 'India may win the match'
or ' I may be selected for this post.' These phrases involve an element of uncertainty. How can
we measure this uncertainty ? A measure of this uncertainty is provided by a branch of
Mathematics, called the theory of probability. Probability Theory is designed to measure the
degree of uncertainty regarding the happening of a given event. The dictionary meaning of probability
is ' likely though not certain to occur. Thus, when a coin is tossed, a head is likely to occur but may
not occur. Similarly, when a die is thrown, it may or may not show the number 6.
In this lesson, we shall discuss some basic concepts of probability, addition and multiplication
theorem of probability and applications of probability in our day to day life.
 
OBJECTIVES
 
After studying this lesson, you will be able to :
l define probability of occurance of an event;
l cite through examples that probability of occurance of an event is a non-negative fraction,
not greater than one;
l use permutation and combinations in solving problems in probability;
l state and establish the addition theorems on probability and the conditions under which
each holds;
l generalize the addition theorem of probability for mutually exclusive events;
l state the multiplication theorem on probability for any two events;
l state and prove the multiplication theorem on compound probability for independent events;
l solve problems on probability using addition and multiplication theorems;
l define conditional probability of an event; and
l solve problems involving conditional probability.