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 \(\sqrt{\frac{\sum fx^2}{\sum f}-\bar{x}^2}\) |
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 | \(4\) | \(6\) | \(13\) | \(7\) |
Using the class midpoints, calculate estimates of the mean and standard deviation.
Video Solution:
Video solution locked
A free account saves your progress; this video needs a course plan.
Solution:
Solution locked
680+ questions here come with free worked solutions. A free account saves your questions and progress; this one needs a course plan.
Create a free account to practise similar questions.
Answer:Estimated mean \(136/30\approx4.53\) accesses per day; estimated standard deviation \(1.91\) accesses (3 s.f.).
Need help? Join our E-Maths tuition for O-Level success.
Learn more