Iodine-125 is radioactive and has a half life of 60.25 days. What percentage of a sample would be left after 21.3 days?Round your answer to 2 significant digits.

To solve this problem, we need to use the formula for exponential decay which is:

N = N0 * (1/2)^(t/T)

where: N is the final amount, N0 is the initial amount, t is the time that has passed, and T is the half-life of the substance.

In this case, we want to find N, the final amount of Iodine-125 left after 21.3 days. We know that the half-life T is 60.25 days. We can assume that the initial amount N0 is 100% since we want to find the final amount as a percentage of the initial amount.

So, we substitute these values into the formula:

N = 100% * (1/2)^(21.3/60.25)

Now, we just need to calculate this expression.

First, calculate the exponent: 21.3/60.25 = 0.3535

Then, calculate the power: (1/2)^0.3535 = 0.7079

Finally, multiply by 100% to find N: 100% * 0.7079 = 70.79%

So, after 21.3 days, approximately 70.79% of the Iodine-125 sample would be left.

Rounding to 2 significant digits, the answer is 71%.