Element X is a radioactive isotope such that every 69 years, its mass decreases by half. Given that the initial mass of a sample of Element X is 20 grams, how much of the element would remain after 30 years, to the nearest whole number?

Step-by-step explanation:

Since the mass of the radioactive isotope is halved every 69 years, we want to multiply its initial mass by every 69 years.

We can model this using the following equation:

The remaining mass, , is equal to the initial mass multiplied by , where is the number of years that have passed from the initial mass. The reason why the exponent is is because we only want to half the mass every 69 years, so and .

Thus, we have:

Substituting , we get:

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )