CLASS 7TH | UNIT 5: DATA HANDLING (STATISTICS) | DATA HANDLING | REVISION NOTES

• Data collection, recording, and presentation assist us in organising and concluding from our experiences.
• We need to know what we are going to do with the data before we start collecting it. The information gathered should be organised in a table that is easy to grasp and analyse.
• The average of a set of numbers can be calculated by finding the sum of the numbers divided by the total numbers of values (n)(n) in the set. 
• The mean, median and mode of a data set are collectively known as measures of central tendency.  
• One of the representative values of data is the arithmetic mean.Mean = sum of all observationsnumber of all observationsMean = sum of all observationsnumber of all observations
• Another type of central tendency or representative value is mode. The most common observation in a group of observations is called the mode. If each value in a data set occurs only once, then all of the values are in mode.
• We sometimes refer to this data as having no mode because none of them occurs frequently.
• The median is a type of representative value as well. It’s the value in the middle of the data set, with half of the observations above it and the other half below it.

Median = 12[n2th observation + (n2+1)th observation]Median = 12[n2th observation + (n2+1)th observation].

• A bar graph is a visual representation of numbers made up of uniformly sized bars. Double bar graphs make it easy to compare two sets of data at once.
• Double bar graphs make it easy to compare two sets of data at once. In our lives, there are events that are certain to occur, some that are impossible to occur, and still others that may or may not occur.
• The situation, which may or may not occur, has a possibility to occur.
• Probability is an area of mathematics that may be used to calculate the probability of an event occurring (in percentage terms). If you have ten likelihoods and want to determine the probability of one event occurring, you might say that the probability is 110110or the event has a 10%10% chance of occurring.
• Events with multiple possibilities can have a probability ranging from 00 to 1.1..