A sample was collected from a computer keyboard and a toilet seat using two separate cotton swabs. Then, each swab was wiped on
1 answer:
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The answer is 1/8.
Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1.
,
where:
<span>n - a number of half-lives
</span>x - a remained fraction of a sample
2.
where:
<span>
- half-life
</span>t - <span>total time elapsed
</span><span>n - a number of half-lives
</span>
The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
<span> = 28.8 years
We need:
n = ?
x = ?
</span>
We could first use the second equation, to calculate n:
<span>If:
,
</span>Then:
⇒
⇒
<span>⇒ n ≈ 3
</span>
Now we can use the first equation to calculate the remained amount of the sample.
<span>
</span>⇒
⇒
<span>
</span>
Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1.
where:
<span>n - a number of half-lives
</span>x - a remained fraction of a sample
2.
where:
<span>
</span>t - <span>total time elapsed
</span><span>n - a number of half-lives
</span>
The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
<span>
We need:
n = ?
x = ?
</span>
We could first use the second equation, to calculate n:
<span>If:
</span>Then:
⇒
⇒
<span>⇒ n ≈ 3
</span>
Now we can use the first equation to calculate the remained amount of the sample.
<span>
</span>⇒
⇒
</span>
Explanation:
1)
a) Wavelength of red light = 700 nm
1 nanometer =
Wavelength of red light in meter will be:
b) Wavelength of red light =
1 meter = 39.3701 inches
Wavelength of red light in inches will be:
2)
Value of distance given = 90.123 km
1 km = 3280.84 feet
1 foot = 0.1515152 chain
Value of distance in chains: