Strontium- 90 is a radioactive material that decays according to the function \( A(t)=A_{0} e^{-0.0244 t} \), where \( A_{0} \) is the initial amount present and \( A \) is the amount present at time \( t \) (in years). Assume that a scientist has a sample of 800 grams of strontium- 90 . (a) What is the decay rate of strontium- 90 ? (b) How much strontium-90 is left after 10 years? (c) When will only 200 grams of strontium- 90 be left? (d) What is the half-life of strontium- 90 ?

3) \( \tan \frac{7 \pi}{12} \)

Solve for \( x \) using the square root property. \( 10(p-4)^{2}-20=470 \) \( p= \) Entry Tip: Do not use a decimal approximation for square roots. To enter a number like \( 5 \sqrt{7} \), type \( 5^{*} \) sqrt( 7 ). Preview your answer before submitting! Furthere Tip: Write your answers as a list, with your answers separated by (a) comma(s). For example, if you get 4 and \( -\frac{2}{3} \) as your answers, then enter \( 4,-2 / 3 \) in the box.

A researcher collects a simple random sample of grade-point averages of statistics students, and she calculates the mean of this sample. Under what conditions can that sample mean be treated as a value from a population having a normal distribution? Select all that apply. \( \square \) A. The researcher collects more than 30 samples. \( \square \) B. If the population of grade-point averages has a normal distribution. \( \square \) C. The sample has more than 30 grade-point averages. \( \square \) D. If the population of statistics students has a normal distribution.

Factor by grouping. \[ 4 w^{5}-7 w^{4}+8 w-14 \]

\( \rightarrow \) Suppose you chose to convert \( \frac{3}{4} \% \) to a fraction using the definition of percent. Complete each equation. \( \begin{array}{l}\frac{3}{4} \div \frac{3}{4} \\ \frac{3}{4}\end{array} \) \( =\frac{3}{400} \)