An element with mass 130 grams decays by 22% per minute. How much of the the element is remaining after 7 minutes, to the nearest 10th of a gram?

1 Answer
Jun 19, 2018

22.8 color(white)(l) "g"

Explanation:

The sample decays by 22% each minute, indicating that the mass at the beginning of the next minute would be 1-22%=78% the mass at the beginning of this minute.

This process repeats for seven times in the 7 color(white)(l) "minutes". That is

130 color(white)(l) "g" xx (1-22%)^7=22.8 color(white)(l) "g"