Question

Element X has a​ half-life of 9 days. If we currently have a 29 ounce sample of Element​ X, how long will it be until only 6 ounces​ remain?

ROUND YOUR ANSWER TO 2 DECIMAL PLACES

Answer 1

6 / 29 = n n = .207 of sample remaining after n half-lives

.5^n = .207 where n is number of half-lives elapsed

n = ln .207 / ln .5 = 2.27 half lives

9 days * 2.27 = 20.5 days for 6 oz to remain

Check:

.5^2.27 = .207 amount left after 2.27 half lives

29 * .207 = 6 oz