Chapter 16

Probability

Sometimes we say, “probably it may rain” or “Probably he may get more than 90% in the examination" etc. These are elements of certainty. Means we are not certain about some things. In mathematics these comes under Probability.

The theory of probability is widely used in the area of natural as well as social science.

Probability as a Measure of Uncertainty

Suppose we through a die which is a well balanced cube with its six faces marked numbers from 1 to 6, one number of one face, we see the number which come up on its uppermost face. A die can fall with any of its face upper most.

The number on each of the face is equally libely and possible outcome. There are six equally likely ealy outcomes: 1, 2, 3, 4, 5 or 6 in a single throw of a die. The chance of any number ‘say 3’ to come up is 1 out of 6. That is probability of 3 coming up is 1/6
i.e. p(3) = 1/6

Similarly in tossing a coin, we may get either head (H) or tail (T) up and P(H) = ½ .............