Question

You have 784 grams of a radioactive kind of tellurium. If its half-life is 42 minutes, how much will be left after 126 minutes?

Answer 1

98 grams

Explanation:

The simplest way to think about this is that the half life has elapsed 3 times, so you need to take the initial mass and divide it by 2 3 times, so 784/2/2/2 or 784/8 which is 98