If
is the amount of strontium-90 present in the area in year
, and it decays at a rate of 2.5% per year, then

Let
be the starting amount immediately after the nuclear reactor explodes. Then

or simply

So that after 50 years, the amount of strontium-90 that remains is approximately

or about 28% of the original amount.
We can confirm this another way; recall the exponential decay formula,

where
is measured in years. We're told that 2.5% of the starting amount
decays after 1 year, so that

Then after 50 years, we have

Answer:
her language arts hw takes longer and it takes 2/9 hr longer
Step-by-step explanation:
first of all, 4/9 > 2/9
4/9-2/9=2/9
What????????????
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Answer:
0.45/1 = (0.45 × 100)/(1 × 100) = 45/100.
Step-by-step explanation: