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Counting is a crucial part of Fundamental Mathematics. Basic mathematics and all mathematical formulas are derived from numbers and the relations they hold amongst them. Probability is the Mathematical branch dealing with chances and likeliness of a particular outcome out of all the possible outcomes that can occur. A Probability Event gives the measure of chances of a Favorable /desired /wanted outcome to be the final outcome of the probability event. Probability largely deals with numbers and the chances of occurrence of different numbers.
There are five basic stages of counting. Starting from Count all, Count on, Maintain cardinality, stable order, and conservative. Let's take a look at all these stages in detail,
1. Count All
Count all the entities irrespective of the order of the entities, keeping intact the abstraction of different entities. Entities are considered equal while counting, there is no discrimination based on the shape, size, or characteristics of an entity.
2. Count On
Group entities as and when required according to the ask and need of the problem statement. One-to-one Mapping is followed while counting different entities. Each entity that needs to be considered, is only counted once.
3. Maintain Cardinality
Cardinality is important with counting. Recounting should not be practiced, each entity needs to be counted only once. There needs to be no recounting with respect to any of the given entities.
4. Stable Order
By stable order, it means that the total number of entities must be a maximum numerical value. Order Irrelevance is the most important stage while considering counting different entities i.e. No fixed order is followed, while counting different entities
5. Conservation
The count of entities remains the same, irrespective of the proximity of different entities. The distance between the entities is irrelevant while considering the count of different entities. Entities that are placed far away will have the same count as entities that are placed closer to each other if they are the same in number.
Counting in Probability stands for considering the count/ different ways of choices or options available to choose amongst the given entities. The count of choices is determined by the available entities.
The different stages of Counting deal with the Fundamental Principle of Counting. The Fundamental Principle of Counting thus is very important aspect considering the probability of available choices for numbers.
The Fundamental Principle of Counting says that for every available entity having 'n' choices related with it, then the total number of ways linked to it will be,
n1 × n2 × n3 × n4...
Steps in Fundamental Principal of Counting
Question 1: A teacher has 10 White chalks and 3 Slate Boards. In how many ways can she select a chalk and slate board ?
Solution:
Choices available for White chalks = 10
Choices available for Slate Boards = 3
Number of Ways for Choosing can take place by the teacher = Choices available for White chalks x Choices available for Slate Boards
= 10 × 3
= 30
Question 2: A boy has choices for 8 Sausages and 4 types of Bread. In how many ways can she select one Sausage an one type of Bread ?
Solution:
Choices available for Sausages = 8
Choices available for Bread = 4
Number of Ways for Choosing can take place by the Boy = Choices available for Sausages x Choices available for Bread
= 8 × 4
= 32
Question 3: Consider a girl having choices to select among 5 Dresses and 4 Snickers.
Solution:
Choices available for Dresses = 5
Choices available for Snickers = 4
Number of Ways for Choosing can take place by the Girl = Choices available for Dresses × Choices available for Snickers
= 5 × 4
= 20
Question 4: A teacher has 27 notebooks and 2 pen: red and blue. In how many ways can she select a notebook and pen ?
Solution:
Choices available for notebooks = 27
Choices available for pen = 2
No. of Ways for Choosing can take place by the teacher = Choices available for notebooks x Choices available for pen
= 27 × 2
= 54
Question 5: Consider a couple having choices to select among 8 Starters and 6 Desserts for Dinner.
Solution:
Choices available for Starters = 8
Choices available for Desserts = 6
Number of Ways for Choosing can take place by the couple = Choices available for Starters × Choices available for Desserts
= 8 × 6
= 48
Question 6: Consider a girl having choices to select among 10 Dresses and 15 Hairbands.
Solution:
Choices available for Dresses = 10
Choices available for Hairbands = 15
Number of Ways for Choosing can take place by the Girl = Choices available for Dresses × Choices available for Hairbands
= 10 × 15
= 150
Question 7: Consider a girl having choices to select among 3 Dresses and 2 Snickers.
Solution:
Choices available for Dresses = 3
Choices available for Snickers = 2
Number of Ways for Choosing can take place by the Girl = Choices available for Dresses × Choices available for Snickers
= 3 × 2
= 6