3) Evaluate without a calculator. Show your work. \( \begin{array}{ll}\text { a) } \log _{2} 16 & \text { b) } \log _{3} 81\end{array} \)

\( \frac{4}{1\times 2}+\frac{4}{2\times 3}+\frac{4}{3\times 4}+...+\frac{4}{23\times 24} \)

The postal service of a country charges \( \$ 0.36 \) postage for a letter weighing up to 1 ounce, plus \( \$ 0.26 \) for each additional ounce up to 5 ounces. Letters weighing more than 5 ounces do not qualify for these rates. \( C(x)=\left\{\begin{array}{ll}\$ \square & \text { if } 0<x \leq 1 \\ \text { (a) Write a piecewise-defined function } C \text { for the postage charged for a letter weighing } x \text { ounces. } \\ \$ \square & \text { if } 3<x \leq 4 \\ \$ \square & \text { if } 4<x \leq 5\end{array}\right. \)

Calcula las siguientes potencias: \( \begin{array}{ll}\text { a) } 3^{-4}=\frac{\square}{\square} & \text { b) }(3 / 4)^{-2}=\frac{\square}{\square}\end{array} \)

A 25 -year old woman burns \( 350-70 t \) cal/hr while walking on her treadmill. Her caloric intake from drinking Gatorade is \( 135 t \) calories during the \( t \) th hour. What is her net decrease in calories after walking for 4 hours?

5 State which consecutive whole numbers are either side of: \( \begin{array}{lll}\text { a } \sqrt{29} & \text { b } \sqrt{40} & \text { c } \\ \text { 7II }\end{array} \)