Statistics

Statistics is the branch of mathematics concerned with:

• collecting and recording data
• sorting and tabulating that data
• presenting data visually in charts and diagrams
• making calculations
• interpreting results.

Handling data

Tally charts and frequency table

One way to organize data is by using table. In a frequency table we can use tally marks to record and display the frequency of events.

Example: Make a frequency table to organize the temperature data in the chart at the right.

A bar graph compares different categories of data by showing each as a bar whose length is related to the frequency.

Example: The below bar chart shows the data from the spelling test.

 A line graph usually shows how data changes over a period of time.

Pictograms convey information through the use of symbols.

The pictograph below shows the number of best film awards that have been given to 5 different movie students.

Choose the correct answer:

1)    How many more students have dog than a turtle?

(a)	9		(b) 2		(c) 7		(d) 8

2) A spinner landed on “red” 6 times, “blue” 4 times, and “green” 5 times. Which tally chart shows these results?

Averages:

Measures of central tendency are numbers used to represent a set of data. Three types of measures of central tendency are mean, median, and mode.

Mean:

The mean is the sum of the numbers in a set of data divided by the number of items.

Mean =

Median: The median is the middle number in a set of data when the data arranged in numerical order (ascending). If there are even numbers of data, the median is the mean of the middle numbers.

Mode: the mode is the number or numbers that appear most often in a set of data. If no item appears most often, the set has no mode.

Example: Example: Find the mean, median and mode values from the given marks: 20, 30, 50, 70, 30, 60

Mean ==43.33

Median:

Arrange the given marks as, 20, 30, 30, 50, 60, 70

There is an even number of values.

Median = =40

Mode:

30 occur 2 times.

Mode = 30