Answer:
You start with 720 grams of element X, which has a half life of 9 minutes. How much time will it take until only 255 grams remain?
elapsed time = half life * log (beginning amount / ending amount) / log 2
elapsed time = 9 * log (720 / 255) / log (2)
elapsed time = 9 * log (2.8235294118
) / log (2)
elapsed time = 9 * 0.450792316 / 0.30102999566
elapsed time = 9 * 1.4974996595
elapsed time = 13.4774969355 minutes
Since the problem wants this rounded to the nearest tenth of a minute:
elapsed time = 13.5 minutes
Step-by-step explanation:
