Chapter 4.2, Problem 63PE

Strontium-90 $\left({}^{90}\text{Sr}\right)$ is a by-product of nuclear fission with a half-life of approximately 28.9 yr., After the Chernobyl nuclear accident in 1986, large areas surrounding the site were contaminated with ${}^{90}\text{Sr}$. If 10 $\mu g$ (micrograms) of ${}^{90}\text{Sr}$ is present in a sample, the function $A\left(t\right)=10{\left(\frac{1}{2}\right)}^{t/28.9}$ gives the amount $A\left(t\right)\left(\text{in }\mu \text{g}\right)$ present after t years. Evaluate the function for the given values of t and interpret the meaning in context. Round to 3 decimal places if necessary. (See Example 5)

a. $A\left(28.9\right)$

b. $A\left(57.8\right)$

c. $A\left(100\right)$