Задача 60507.

There are 12 g of a radioactive substance, whose half-life is 19 minutes. After what time will disintegrate 9 g of this substance. The answer is to express in minutes.

Detailed solution with a brief record of the conditions, formulas and laws used in the decision, the conclusion of the calculation formula and the answer.
If you have any questions about the decision, write. I will try to help.