Isotopic$-$dilution analysis is widely used in the pharmaceutical industry. The method

consists of mixing n measured amount of radioactive compound with the unknown and

then measuring the extent to which it is diluted. $1$ g of radioactive penicillin registering

$9,000$ counts$/$min on a Geiger counter is added to a fermentation broth containing an

unknown amount of penicillin. After a complicated series of extractions which recover

$85\%$ of all the penicillin as a crystalline product, the Geiger counter now reads $3$

counts$/$min$.$ What was the total amount of penicillin in the fermentation broth?