Answer: 262,785
Note: you may need to delete the comma
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Step-by-step explanation:
The info "5 months" is never used to compute the mean. We could easily replace it with "6 months" or "7 months" or any stretch of time, and still get the same answer. So we'll ignore this value.
What we'll do is add up the 21 items given to us, and then divide by 21.
Because there are so many values, and it's easy to get lost, I'm going to add up across the rows
- Row One: 256,229+253,657+218,747+246,163+235,626+288,694 = 1,499,116
- Row Two: 316,265+196,721+319,620+285,077+215,152+253,291 = 1,586,126
- Row Three: 315,011+199,901+265,443+291,806+303,556+215,359 = 159,1076
- Row Four: 258,554+293,658+289,935 = 842,147
Those subtotals then add up to this
1,499,116+1,586,126+1,591,076+842,147 = 5,518,465
This is the same as adding up all 21 values.
Finally, we divide that sum over 21 as there are 21 values in this list
(5,518,465)/21 = 262,784.047619048
That value then rounds up to 262,785
If your teacher just wanted things to the nearest whole number (without rounding up), then the answer would be 262,784
Side note: using a spreadsheet program would probably be the most efficient/fastest method for this type of problem.