1970 AHSME Problems/Problem 19

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Problem

The sum of an infinite geometric series with common ratio $r$ such that $|r|<1$ is $15$, and the sum of the squares of the terms of this series is $45$. The first term of the series is

$\text{(A) } 12\quad \text{(B) } 10\quad \text{(C) } 5\quad \text{(D) } 3\quad \text{(E) 2}$

Solution

$\fbox{C}$

See also

1970 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 18
Followed by
Problem 22
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