Question

If you have 10,000 grams of a substance that decays with a half-life of 14 days, then how much will you have after 70 days?

Answer 1

If the substance has a half-life of 14 days, then we know that after every 14 days, the amount of the substance remaining will be divided by two.

Since 70 days is five half-lives (70 ÷ 14 = 5), we can find the amount of substance remaining after 70 days by dividing the initial amount by 2 five times.

Amount remaining = 10,000 grams / (2^5) = 10,000 grams / 32

Amount remaining = 312.5 grams

Therefore, after 70 days, you will have 312.5 grams of the substance remaining.