What is Statistics?

Statistics is the study of collecting, organizing, summarizing, and interpreting data.

Types of Data

Primary Data: Collected for the first time by the researcher

Secondary Data: Already collected by someone else (books, websites, records)

Frequency & Relative Frequency

Frequency: Number of times a value appears in the data

Relative Frequency: Frequency ÷ Total number of values

Graphs

Bar Graph

Compares different groups or categories

Bars are separated by spaces

Height = frequency

Line Graph

Shows changes over time

Points plotted and joined with lines

Measures of Central Tendency

Mean = Average = (Sum of all values) ÷ (Total number of values)
Median = Middle value (if even, average of two middle values)
Mode = Most repeated value

Range

Range = Highest value − Lowest value
Shows how spread out the data is

Quartiles & IQR

Q1: Median of lower half

Q2: Median of whole data

Q3: Median of upper half

IQR = Q3 − Q1 → spread of middle 50% of data

Box-and-Whisker Plot

Shows 5 values: Minimum, Q1, Median, Q3, Maximum

Cumulative Frequency

Running total of frequencies from first to last

5 Common & Important Questions (with Answers)

Q1. Find the mean of 5, 10, 15, 20
Sum = 50, Mean = 50 ÷ 4 = 12.5

Q2. Find the median of 8, 3, 5, 2, 9
Ordered: 2, 3, 5, 8, 9 → Median = 5

Q3. Find the mode of 4, 6, 7, 4, 8, 4, 9
Most repeated value = 4

Q4. Find the range of 12, 18, 25, 10, 20
Range = 25 − 10 = 15

Q5. For data 4, 6, 8, 10, find Q1, Q2, Q3
Ordered: 4, 6, 8, 10
Q2 = (6+8)/2 = 7
Q1 = (4+6)/2 = 5
Q3 = (8+10)/2 = 9

Visit this link for further practice!!

https://besidedegree.com/exam/s/academic