Question

48 grams of a radioactive substance decayed 15% over the course of 9 weeks. How many grams of the substance were left after the 9 weeks?

A. 40.8 grams
B. 44.6 grams
C. 51.2 grams
D. 55.2 grams

Answer 1

After 9 weeks, 40.8 grams of the radioactive substance will be left.

Step-by-step explanation:

To find the amount of the radioactive substance that remains after the 9 weeks, we can use the formula:

Amount remaining = Initial amount * (1 - decay rate)

Given that the decay rate is 15% (or 0.15) and the initial amount is 48 grams, we can substitute these values into the formula:

Amount remaining = 48 grams * (1 - 0.15) = 48 grams * 0.85 = 40.8 grams

Therefore, after the 9 weeks, 40.8 grams of the substance will be left.