Mean and Standard Deviation of Grouped Data
Mean and Standard Deviation of Grouped Data
Secondary 4
Formula to find mean of a set of data Grouped Data: \(\frac{\sum fx}{\sum f}\) |
Formula to find standard deviation \(\sqrt{\frac{\sum x^2}{n} - \bar{x}^2} \text{ or}\hspace{0.5em} \sqrt{\frac{\sum (x - \bar{x})^2}{n}}\) |
The frequency table shows the distribution of the number of times a class of \(30\) students access Facebook in a day.
Number of access to Facebook (daily) | \(0 < t \le 2\) | \(2 < t \le 4\) | \(4 < t \le 6\) | \(6 < t \le 8\) |
|---|---|---|---|---|
| Number of students | \(4\) | \(6\) | \(13\) | \(7\) |
Calculate the mean and standard deviation of this data.
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Answer:Mean \(4\frac{8}{15}\) accesses per day; standard deviation \(1.91\) accesses (3 s.f.).
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