Question

A patient ingested barium−131. How much time will elapse until only 1/32 of the barium−131 remains, assuming that none of the isotope is eliminated from the body through normal processes? Answer in minutes

Answer 1

`72000 " minutes"`

Explanation:

We could use the direct equation for a half-life or, as in this case, go by fractions because of the even divisibility.
1 -> 1/2 -> 1/4 -> 1/8 -> 1/16 -> 1/32 is Five half-lifes.

The half-life of Barium-131 is 10 days, so five of them is 50 days. Assuming a 24-hour day, that would be `50 xx 24 xx 60 = 72000 " minutes"`

See also the following for an example of the formula solution:
https://socratic.org/questions/barium-131-is-a-radioactive-isotope-of-the-element-barium-used-gastrointestinal-