MathDB
Two Sequences

Source:

January 1, 2009
arithmetic sequencegeometric sequencegeometric series

Problem Statement

If a a, b b, c c, and d d are positive real numbers such that a a, b b, c c, d d form an increasing arithmetic sequence and a a, b b, d d form a geometric sequence, then ad \frac{a}{d} is <spanclass=′latex−bold′>(A)</span> 112<spanclass=′latex−bold′>(B)</span> 16<spanclass=′latex−bold′>(C)</span> 14<spanclass=′latex−bold′>(D)</span> 13<spanclass=′latex−bold′>(E)</span> 12 <span class='latex-bold'>(A)</span>\ \frac{1}{12} \qquad <span class='latex-bold'>(B)</span>\ \frac{1}{6} \qquad <span class='latex-bold'>(C)</span>\ \frac{1}{4} \qquad <span class='latex-bold'>(D)</span>\ \frac{1}{3} \qquad <span class='latex-bold'>(E)</span>\ \frac{1}{2}
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