Berringer Designs hired a graphic artist. It is estimated that the artist$$s learning rate is at $70\%$ and her first quarter$$s output amounted to $300$ relatively equal job outputs, which took her a total of $50$ hours to complete. Output is expected to double in every succeeding quarter.

By the $5$th quarter, based on learning curve estimates, what should the artist$$s average time $($in hours$)$ be for the units of output?

Multiple Choice

$17\mathrm{.}15$ hours

$3\mathrm{.}5$ hours

$12\mathrm{.}005$ hours

$6\mathrm{.}9$ hours

None of the answers is correct