Element X decays radioactively with a half life of 15 minutes. If there are 400 grams of Element X, how long, to the nearest tenth of a minute, would it take the element to decay to 87 grams?

The time it'd take for the element to have 15 g of mass is approximately 68 min.

Step-by-step explanation:

The radioactive decay of a substance is given by the following formula:

Since the element has a half life of 12 minutes, this means that after this time the mass of the element will be half of it was originally, therefore:

Therefore the mass of the element is given by:

If the initial mass is 760 g and the final mass is 15 g, we have:

The time it'd take for the element to have 15 g of mass is approximately 68 min.

Step-by-step explanation:

168

step-by-step explanation:

i am pretty sure that the answer is 168

exa:

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3+11

14

step-by-step explanation:

from this example, we can see that subtracting with integers is the same as adding the opposite. we can solve using a number line or by using the saying "keep, change, change" to us solve. it is important to remember that we can subtract a negative and end up with a larger number than we started with.