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The first and last terms of a 10-term arithmetic series are listed in the table. What is the sum of the series?



Term Number Term

1 3

10 75

Verified Answer :

naǫ

The sum of an arithmetic series:
\(S_n=\frac{n(a_1+a_n)}{2}\)

\(a_1=3 \\ a_{10}=75 \\ \\ S_{10}=\frac{10(a_1+a_{10})}{2}=\frac{10(3+75)}{2}=5(3+75)=5 \times 78=390\)

The sum of the series is 390.

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