Page 192 - DMTH202_BASIC_MATHEMATICS_II

Unit 14: Probability

Instances of random experiments are: Notes
1. Tossing a die,
2. Calculating the amount of rainfall in January,
3. Counting the number of calls coming at a telephone exchange throughout a fixed time
period,
4. Choosing a random model of fifty people and scrutinizing the number of left-handers,
5. Selecting at random ten people and gauging their height.

Example: (Coin Tossing) The most basic random experiment is the experiment where a
coin is tossed a number of times, say n times. Certainly, much of probability theory can be
dependent on this experiment. To better recognize how these experiment performs, we can
perform it out on a digital computer, for instance in Matlab.
The given below simple Matlab program, creates a series of 100 tosses with a fair coin (that is,
heads and tails are uniformly likely), and plots the outcomes in a bar chart.

x = (rand(1,100) < 1/2)
bar(x)
Here x is a vector with 1s and 0s, representing Heads and Tails, say. Distinctive outcomes for
three such experiments are given in Figure 14.1.

Figure 14.1: Three Experiments where a Fair Coin is Tossed 100 Times

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