Average is a numberthat represents or shows the central tendencyof a group of observations or data.

Arithmetic mean is one of the representative values of data.

Mean = sum of all observations/ Number of observations.

Mode is another form of central tendency or representative value.

The mode of a set of observations is the observation that occurs most often.

If each of the value in a data is occurring one time, then all are mode.

Sometimes we also say that this data has no mode since none of them is occurring frequently.

Median is also a form of representative value.

It refers to the value which lies in the middle of the data with half of the observations above it and the other half below it.

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A bar graph is a representation of numbers using bars of uniform widths.

Double bar graphshelp to comparetwo collections of data at a glance.

Double bar graphshelp to comparetwo collections of data at a glance.

There are situations in our life, that are certain to happen, some that are impossible and some that may or may not happen.

The situation that may or may not happen has a chanceof happening.

Probability: A branch of mathematics that is capable of calculating the chance or likelihood of an event taking place (in percentage terms).

If you have 10 likelihoods and you want to calculate the probability of 1 event taking place,it is said that its probability is 1/10 or event has a 10% probability of taking place.

Events that have many possibilities can have probability between 0 and 1.

Important Formulae – Data Handling

1. A trial is anaction which results in one or several outcomes. 2. An experiment in whichthe result ofa trial cannot be predicted inadvance is called a random experiment.

3. An event associated to a random experiment is thecollection of someoutcomes of theexperiment.

4. An event associated witha random experiment is said tohappen if anyone of theoutcomes satisfying thedefinition of theevent is anoutcome of theexperiment when it is performed.

5. The Empirical probability ofhappening of an event E is defined as: P(E)= Number of trials in which the event happened/ Total number of trials.