A data set is summarized by the frequency distribution below, where is a positive integer.
| Value | Frequency |
|---|---|
| 10 | 2k |
| 20 | 3k |
| 30 | k |
| 40 | 2k |
| 50 | 4k |
If the mean of the data set is and the median is , which of the following statements is true?
M \lt N
M = N
M ＞ N
The relationship between M and N cannot be determined without knowing the value of k.
