Question

A

lodine-131, a radioactive substance that is effective in locating brain tumors, has a half-life of only eight days.
hospital purchased 27 grams of the substance but had to wait seven days before it could be used. How much of the
substance was left after seven days?

The amount of substance left after seven days was __ g.
(Round the final answer to three decimal places as needed. Round all intermediate values to seven decimal places as
needed.)

Answer 1

5 days/8 days = 0.625 half lives

fraction left after 0.625 half lives = (1/2)^0.625

= 0.6484197773

Amount left = 27 x 0.6484197773 gms

= 17.51 gms to dp <<<