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Example: If you have the numbers 6, 3, 4, and 7, the mean is calculated as follows:
Mean=6+3+4+7=20/4=5
So, the mean is 5.
• Median: The median is the middle value of a dataset when the numbers are arranged in ascending order.
If there’s an odd number of values, the median is the one right in the middle. If there’s an even number of values,
the median is the average of the two middle numbers.
Example 1 (odd number of data points): For the data 1, 3, 5, 7, 9 the median is 5 because it’s in the middle.
Example 2 (even number of data points): For the data 1, 3, 5, 7, the median is the average of the two middle
numbers, so it is: Median = (3+5)/2=4
• Mode: The mode is the number that appears most often in your data set. If a number appears more times than
any other number, it is the mode.
Example: For the data set 2, 3, 3, 5, 6, 6, 6, the mode is 6, because it appears three times, more than any other
number.
• Distribution: The distribution of a dataset describes the shape of how data values are spread. The shape can
be left-skewed, right-skewed, or normal, and each type of skewness or symmetry tells us something different
about how the data is spread out.
Mode
Median
Mode Mean Mode
Median Median
Mean Mean
Left skewed Normal Distribution Right skewed
• Left Skewed: A left-skewed distribution has a long tail on the left side (toward the lower values) and the
majority of the data is on the right. The mean is usually less than the median, and the median is less than the
mode.
Example: In a group of people’s income, most people might earn a moderate income, but there are a few
people earning extremely low incomes, which pulls the average income lower.
• Normal Distribution (Bell Curve): A normal distribution is perfectly symmetrical and resembles a bell-shaped
curve. The highest point is in the middle, and the tails gradually taper off on both sides. The mean, median, and
mode are all the same and are located at the center.
Example: Heights of people in a large population often follow a normal distribution. Most people will be of
average height, with fewer people being very short or very tall.
• Right skewed: A right-skewed distribution has a long tail on the right side (toward the higher values), and
most of the data is clustered on the left. The mean is usually greater than the median, and the median is
greater than the mode.
Example: In a class’s exam scores, most students might score in the middle range, but a few students could
score extremely high, which pulls the average score higher.
Probability
Probability deals with the likelihood or chance of an event happening. It helps us understand how likely or unlikely
something is to occur based on known information. In simple terms, probability answers the question: “How likely
Statisical Data (Practical) 261

