How much of a radioactive kind of antimony will be left after 120 days if you start with 904 grams and the half-life is 60 days?

 226 grams

Explanation:

1/2 = 0.5

Every 60 days, the amount cuts in half.

We start with 904 grams and after 60 days, we have 904*0.5 = 452 grams left over.

After another 60 days, we have 452*0.5 = 226 grams left over.

Alternative Method:

We can apply the half-life formula.

y = a*(0.5)^(x/H)

where,

y = final amount after x daysa = initial amountx = number of days that elapseH = number of days in a half-life

In this case,

a = 904 is the starting amountH = 60 is the number of days until another half-life occurs

When x = 120 days go by, we have

y = a*(0.5)^(x/H)

y = 904*(0.5)^(x/60)

y = 904*(0.5)^(120/60)

y = 904*(0.5)^(2)

y = 904*(0.25)

y = 226 grams of antimony left over.

This method is preferred over the first method if you have x be some non-multiple of 60, or if x is fairly large.

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Step-by-step explanation: