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2 years ago

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The sum of the first 15 terms of the sequence an=10n+21

1 answer:

enot [183]2 years ago

3 0

That is
the sum of all the terms from a1 to an when you are summing up n terms is n(a1+an)/2
so

find the 1st and 15th term
1st term is a1=10(1)=21=10+21=31
15th term is a15=10(15)+21=150+21=171

and n=15
15(31+171)/2=15(202)/2=3030/2=1515
the sum of the first 15 term is 1515

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What is the solution to this system of linear equations? 7x – 2y = –6 8x y = 3 (–6, 3) (0, 3) (1, –5) (15, –1)

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2 years ago

Read 2 more answers

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Answer:

1) 25

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Step-by-step explanation:

Note: from the question, the number of F2F data is 15 not 12

1) for degree of freedom:

12 + 15 - 2 = 25

2) formula for standard error:

$S_e_r = A/(sqrt*N)$

But A is standard deviation. To find the standard deviation we use:

S.d = [sqrt*(E(xi - u)^2) / N]

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u = individual data

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$(85.7-95)^2 = 86.49$

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$S.d = sqrt*[(E(xi-u)^2)/N]$

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2 years ago

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2 years ago