Calculate the variance of 2, 3, 3, 4, 5, 5, 5, 7, 7 and 9
Answer Details
To calculate the variance of a set of data, you need to follow these steps:
1. Find the mean of the data set.
2. For each data point, subtract the mean and square the result.
3. Add up all the squared differences.
4. Divide the sum of squared differences by the total number of data points minus one.
Here are the steps for the given data set:
1. Find the mean:
(2 + 3 + 3 + 4 + 5 + 5 + 5 + 7 + 7 + 9) / 10 = 5
2. Subtract the mean and square the result for each data point:
(2 - 5)^2 = 9
(3 - 5)^2 = 4
(3 - 5)^2 = 4
(4 - 5)^2 = 1
(5 - 5)^2 = 0
(5 - 5)^2 = 0
(5 - 5)^2 = 0
(7 - 5)^2 = 4
(7 - 5)^2 = 4
(9 - 5)^2 = 16
3. Add up all the squared differences: 9 + 4 + 4 + 1 + 0 + 0 + 0 + 4 + 4 + 16 = 42
4. Divide the sum of squared differences by the total number of data points minus one:
42 / (10 - 1) = 4.67
Therefore, the variance of the given data set is approximately 4.67. The closest option is 4.2.