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bekas
2 months ago
9

A series contains 18 numbers and has a sum of 4,185. The last number of the series is 275. What is the first number?

Mathematics
1 answer:
Inessa [12.5K]2 months ago
3 0
The formula for the sum of an arithmetic series is expressed as:
Sn=n/2(a1+an)
where:
n=total terms
a1=the initial term
an=the final term
given
n=18, an=275, Sn=4185
substituting these values into the equation results in:
4185=18/2(a1+275)
after simplification, we obtain:
4185=9(a1+275)
dividing by 9 yields:
465=a1+275
therefore
a1=465-275
a1=190

Conclusion: the first term is 190
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Find the standard deviation of the following data. Answers are rounded to the nearest tenth. 5, 5, 6, 12, 13, 26, 37, 49, 51, 56
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The data type involved is ungrouped

standard deviation =√ [∑ (x-μ)² / n]

average (μ)=∑x/n

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For the values 5, 5, 6, 12, 13, 26, 37, 49, 51, 56, 56, 84, the x-μ results will be

                   -28.3, -28.3, -27.3, -21.3, -7.3, 3.7, 15.7,17.7, 22.7,22.7,50.7

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