Random Experiment and Outcomes

The words may, likely, unlikely, chances, doubt show that the event, we are talking about , is not certain to occur. It may or may not occur. Theory of probability is a branch of Mathematics which has been developed to deal with situations involving uncertainty.

The theory had its beginning in the 16th century. It originated in the games of chance such as throwing of dice and now probability is used extensively in Biology, Economics, Genetics, Physics, Sociology, etc.

(1) Coin

Suppose we toss a coin. We know in advance that the coin can only land in one of two possible ways that is either Head (H) up or Tail (T) up.

(2) Dice

Suppose we throw a die. We know in advance that the die can only land in any one of six different ways showing up either 1, 2, 3, 4, 5 or 6.

(3) Seeds

Suppose we plant 4 seeds and observe the number of seeds germinated after three days. The number of germinated seeds could be either 0, 1, 2, 3, or 4.

In the above situations, tossing a coin, throwing a die, planting seeds, each is an example of a random experiment.

In (1), the possible outcomes of the random experiment of tossing a coin are: Head and Tail. In (2), the possible outcomes of the experiment are: 1, 2, 3, 4, 5, 6. In (3), the possible outcomes are: 0, 1, 2, 3, 4.

A random experiment always has more than one possible outcomes. When the experiment is performed, only one outcome out of all possible outcomes comes out. Moreover, you can not predict any particular outcome before the experiment is performed. Repeating the experiment may lead to different outcomes.

Examples of Random Experiments

(4) Balls in a Bag

Drawing a ball from a bag containing identical balls of different colours without looking into the bag.

(5) Playing Cards

Drawing a card at random from a well shuffled deck of playing cards. A deck of playing cards consists of 52 cards which are divided into four suits of 13 cards each - spades, hearts, diamonds and clubs. Spades and clubs are of black colour and others are of red colour. The cards in each suit are ace, king, queen, jack, 10, 9, 8, 7, 6, 5, 4, 3, and 2. Cards of kings, queens and jacks are called face cards.