# Probability : What it is?

## Probability : Meaning, Synonyms, Antonyms

### Meaning

1. A measure of how likely it is that some event will occur

1. Likelihood
2. chance
3. prospect
4. odds
5. possibility

### Antonyms

1. Improbability

## Probability » The Chance of occurrence

Probability is all about expressing the chance of occurrence of an event on a one scale.

1. Question : How did you write your exams?
Reply : The paper was tough, I have a 60% chance of getting through.
Reply reframed : The probability of me getting through the exam is 0.6
→ → Event Getting through the examination. Chance 0.6
2. Question : Will the principal give us permission for going on a picnic?
Reply : He is an understanding person. He knows and accepts the importance of picnics for children.

There is a 95% chance for the principal to permit us.

Reply reframed : The probability for the principal to permit us to go on a picnic is 0.95
→ → Event The principal permitting the students to go on a picnic. Chance 0.95
3. Question : I am tossing this coin. Can you say whether it will show up Heads or Tails?
Reply : The coin may show up either Heads or Tails. Both have a equal chance of occurrence. 50% for Heads and 50% for tails.
Reply reframed : The probability for the coin to show up heads is 0.5 and to show up tails is 0.5
The event here can be assumed in two ways

 Event → Getting a HEAD Chance 0.5

→ → Event Getting a TAIL Chance 0.5

Reply reframed: The probability for the coin not to show up heads is 0.5 and not to show up tails is 0.5
The event here can be assumed in two ways

 Event → Not getting a HEAD Chance 0.5

 Event → Not getting a TAIL Chance 0.5
4. Question : There are 10 balls in this bag, 4 of them red and 6 blue. I am picking up one ball. Will it be red or blue?
Reply : The ball drawn may be either red or blue. Since all the balls have an equal chance of being drawn, there is a 4 out of 10 chance that the ball drawn is red and a 6 out of 10 chance that the ball drawn is blue.
Reply reframed : The probability for the ball drawn to be red is 0.4
 Event Drawing a red ball. 0.4
Reply reframed : The probability for the ball drawn to be blue is 0.6
 Event Drawing a blue ball. 0.6

## Occurrence » The three possibilities - For Sure or Always - Never - May or may not

When we think of something happening, we will come across three possibilities with regard to the chance of their occurrence.

### For Sure

It may happen for sure. We say it is certain. If the chance of occurrence of the event is certain, you say that there is a 100% chance of it happening.

This expressed in probability terms would be "The probability of happening of the event is 1"

#### Examples

 Question : 1. How did you write your exams? I was very well prepared. There is no doubt at all. I have a 100% chance of getting through. The probability of me getting through the exam is 1 2. Will the principal give us permission for going on a picnic? He is an understanding person. He knows and accepts the importance of picnics for children. He will permit us for sure. There is a 100% chance. The probability that the principal will permit us to go on a picnic is 1 3. There are 10 balls in this bag, all 10 of them blue. I am picking up two balls. Can you say whether the 2 balls would be blue or not. What color would they be otherwise? Since all the balls are blue, you are sure to get 2 blue balls. There is a 100% chance that the 2 balls drawn are blue. The probability for the balls drawn to be blue is 1 4. I am throwing up a die. Can you say whether I would get any of the numbers 1,2,3,4,5,6 or not. What else would appear? Since the six faces of the dice will have the numbers 1,2,3,4,5,6 on them, one of these should appear for sure. There is a 100% chance that one of the numbers 1,2,3,4,5,6 would appear. The probability for the die to show up either 1,2,3,4,5 or 6 is 1.

### Never : not at all

It may not happen at all. We say it is impossible. If there is no chance of occurrence of the event, we say that there is a 0% chance of its happening.

This expressed in probability terms would be "The probability of the happening of the event is 0".

#### Examples

 Question : 1. How did you write your exams? Very bad. The paper was tough. I was not prepared for the exam. There is no doubt. I would fail. I have a 0% chance of getting through. The probability of me getting through the exam is 0. 2. Will the principal give us permission for going on a picnic? There is a cyclone warning. How do you expect him to send us in such a situation. He will not permit us for sure. There is a 0% chance. The probability that the principal will permit us to go on a picnic is 0. 3. There are 10 balls in this bag, 4 of them white and 6 of them blue. I am picking up two balls. Can you say if I can draw a red ball or not. How is it possible? There are no red balls in the bag and so you there is no way you can draw a red ball. There is a 0% chance that the 2 balls drawn are red. The probability for the balls drawn to be red is 0 4. I am throwing up a die. Can you say whether I would get a multiple of 10 or not. numbers 1,2,3,4,5,6 or not. How can you expect to get the number 10 on the dice? The six faces of the dice have the numbers 1,2,3,4,5,6 on them and only one of those would appear. There is a 0% chance that the number appearing is a multiple of 10. The probability for the die to show up a multiple of 10 is 0.

### May or May not Happen

It may happen or may not happen. We say it is probable. If the chance of occurrence of an event is uncertain, we say that there is a "x"% chance of it happening.

How much is "x"?

It would be dependent on the case in consideration.

This expressed in probability terms would be "The probability of its happening is p [p = x ÷ 100]"

#### Examples

 Question : 1. How did you write your exams? The paper was tough, I have a 60% chance of getting through. The probability of me getting through the exam is 0.6

Probability of an event is an indication of

1. The certainity of occurrence of the event, when its numerical value would be 1;
2. The impossibility of the occurence of the event, when its numerical value would be 0;
3. The chance of the occurrence of an event which is neither impossible nor certain.

Probability is a numeric value which lies between the two extremes, 0 and 1 both numbers inclusive.

## 200%, 300%,.... 1000% Chance!!

What about those instances when we say I have a 200% chance or 500% chance etc. These are wordings used to express the confidence with which we are expressing it and not numerical measures.

When something happens for sure, it is 100% and when it does not happen it is 0% and when it has a certain likelihood of occurrence somewhere in between these extremes it is between 0% and 100% and never 200%, 300%, 500% etc.

Something more than 100% in expressing the possibility of happening of an event should be understood as a qualitative measure rather than a quantitative measure.

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