Question

The half-life of sr-85, which may be used in bone scans, is 64. 8 days. How many milligrams of a 7 mg sample will be left after 127 days? round to the hundredths place

Answer 1

$\textit{Amount for Exponential Decay using Half-Life} \\\\ A=P\left( \frac{1}{2} \right)^{\frac{t}{h}}\qquad \begin{cases} A=\textit{current amount}\\ P=\textit{initial amount}\dotfill &7\\ t=\textit{elapsed time}\dotfill &127\\ h=\textit{half-life}\dotfill &64.8 \end{cases} \\\\\\ A=7\left( \frac{1}{2} \right)^{\frac{127}{64.8}}\implies A=7\left( \frac{1}{2} \right)^{\frac{635}{324}}\implies A\approx 1.80$

Answer 2

The half-life of sr-85, which may be used in bone scans, is 64.8 days. 1.80 milligrams of a 7 mg sample will be left after 127 days.

What is half-life?

Half-life is defined as the time required for a quantity to reduce to half of its initial value.

The half-life of sr-85, which may be used in bone scans, is 64. 8 days.

We need to find how many milligrams of a 7 mg sample will be left after 127 days.

$\rm A = P\frac{1}{2} ^{t/h}$

here A = current amount

P = inital amount

t = time

h = half life

So,

$\rm A = 7\frac{1}{2} ^{127/64.8}$

$\rm A = 7\frac{1}{2} ^{635/324}\\A = 1.80$

Learn more about half-life;

https://brainly.com/question/24710827

#SPJ4