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

35 divided by 2 1/2
change 2 1/2 to an improper fraction
2 1/2 = 5/2
35 divided by 5/2
copy dot flip
35 * 2/5
70/5
14
you can make 14 plots
Answer:
-9w+12wx+3wy
Step-by-step explanation:
just distribute 3w through the parentheses
<span>6 yr 7 months+ 2 yr 11 months = ?
6 yr + 2 yr = 8 yr
7 months + 11 months = 18 months = 1 yr 6 months
8 yr + </span>1 yr 6 months = 9 yr 6 months
answer is C<span>. 9 yr 6 months</span>
C
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