You have 1,312 grams of a radioactive kind of lanthanum. If its half-life is 93 minutes, how much will be left after 279 minutes?

To solve this problem, we first need to determine how many half-lives have passed in 279 minutes.

Step 1: Determine the number of half-lives The half-life of the radioactive lanthanum is 93 minutes. So, we divide the total time by the half-life to find out how many half-lives have passed. 279 minutes / 93 minutes/half-life = 3 half-lives

Step 2: Calculate the remaining amount We start with 1,312 grams of the substance. After one half-life, half of it will remain, so we divide by 2. 1,312 grams / 2 = 656 grams

After the second half-life, we again divide by 2. 656 grams / 2 = 328 grams

And after the third half-life, we divide by 2 once more. 328 grams / 2 = 164 grams

So, after 279 minutes, there will be 164 grams of the radioactive lanthanum left.