Twenty percent of a radioactive substance decays in ten years. By what percent does the substance decay each year?
An investment decreases by 4% per year for 5 years. By what total percent does it decrease after the 5 years?
To find the percentage by which the substance decays each year, we can divide the total decay over ten years (20%) by the number of years (10).
20% / 10 years = 2% per year.
Therefore, the substance decays by 2% each year.
To find the percentage of decay each year, we can use the formula:
Percentage of decay per year = Percentage of total decay / Number of years
In this case, we know that twenty percent decays in ten years. Let's calculate the percentage of decay each year:
Percentage of decay per year = 20% / 10 years
Percentage of decay per year = 2% per year
Therefore, the substance decays by 2 percent each year.