Please explain ---Here is the extracted content from the image:
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**Question 5**
**Question Stem:**
If the mean of the frequency distribution is 28, then its variance is _______.
**Table Content:**
| Class | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 |
| :-------- | :----- | :------ | :------ | :------ | :------ |
| Frequency | 2 | 3 | x | 5 | 4 |
**Other Relevant Text:**
[2023 (10 Apr Shift 1)]
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**Question 6**
**Question Stem:**
Let μ be the mean and σ be the standard deviation of the distribution
where Σf_i = 62. If [x] denotes the greatest integer ≤ x, then [μ² + σ²] is equal to
**Table Content:**
| X_i | 0 | 1 | 2 | 3 | 4 | 5 |
| :-- | :---- | :-- | :------ | :------ | :------ | :---- |
| f_i | k + 2 | 2k | k² - 1 | k² - 1 | k² + 1 | k - 3 |
**Options:**
(1) 9
(2) 8
(3) 7
(4) 6
**Other Relevant Text:**
[2023 (10 Apr Shift 2)]
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视频信息
答案文本
视频字幕
In this video, we'll solve two problems related to mean and variance of frequency distributions. The first problem gives us a frequency distribution table with one unknown frequency x, and tells us that the mean is 28. We need to find the variance.