The following table shows projected worldwide sales of (all) cell phones and wholesale prices:

$$\begin{matrix} \text{Year} & \text{2004} & \text{2008}\\ \text{Wholesale Price (\$)} & \text{100} & \text{80}\\ \text{Sales (millions)} & \text{600} & \text{800}\\ \end{matrix}$$

a. Use the data to obtain a linear demand function for cell phones, and use your demand equation to predict sales if the price was set at $85. b. Fill in the blanks: For every ____ increase in price, sales of cell phones decrease by ___ units.

Worldwide annual sales of all cell phones were approximately −10p+1,600 million phones when the wholesale price was $p. At what wholesale price should cell phones have been sold to maximize annual revenue? What would have been the resulting revenue?

Each ordered pair is from an inverse variation. Find the constant of variation. $(\sqrt{2}, \sqrt{18})$

You work at a clothing store that offers a 15 -percent employee discount. One of the items you and your five friends need for your Halloween costumes is sold at your store. Your friends want you to buy that item in their respective sizes with your employee discount. However, your store policy does not allow this. How would you explain this to your friends?

If the sum of 2/3 and 3/4 is divided by the product of 2/3 and 3/4, what is the quotient?

Graph the given equation. 3x=−2y

During a surge in the demand for electricity, the rate, r, at which energy is used can be approximated by

$$r=t e^{-a t}$$

where t is the time in hours and a is a positive constant.

What happens to E as $T \rightarrow \infty$ ?

Use a graphing utility to solve each equation. Express your answer rounded to two decimal places. $e^{-x}=-\ln x$

The table below shows the number of cell phone subscriptions (in billions) worldwide from 2012 through 2019.

$$\begin{array}{|l|c|c|c|c|} \hline \text { Year } & 2012 & 2013 & 2014 & 2015 \\ \hline \text { Number } & 6.3 & 6.7 & 7.0 & 7.2 \\ \hline \end{array}$$

$$\begin{array}{|l|c|c|c|c|} \hline \text { Year } & 2016 & 2017 & 2018 & 2019 \\ \hline \text { Number } & 7.5 & 7.8 & 7.9 & 8.3 \\ \hline \end{array}$$

Use the model to predict the number of cell phone subscriptions worldwide in the year 2029.

The RideEm Bicycles factory can produce 100 bicycles in a day at a total cost of $10,500 and it can produce 120 bicycles in a day at a total cost of$11,000. What are the company’s daily fixed costs, and what is the marginal cost per bicycle?

If it costs Microsoft $4,500 to manufacture 8 Xbox 360s and$8,900 to manufacture 16, obtain the corresponding linear cost function. What was the cost to manufacture each additional Xbox? Use the cost function to estimate the cost of manufacturing 50 Xboxes.

Solve the linear system using substitution or elimination.

$$\left. \begin{array} { l } { - 16 x + 2 y = - 2 } \\ { y = 8 x - 1 } \end{array} \right.$$

The cost of renting tuxes for the Choral Society’s formal is $20 down, plus$88 per tux. Express the cost C as a function of x, the number of tuxedos rented. Use your function to answer the following questions. a. What is the cost of renting 2 tuxes? b. What is the cost of the 2nd tux? c. What is the cost of the 4,098th tux? d. What is the variable cost? What is the marginal cost? e. Graph C as a function of x.

Worldwide quarterly sales of Nokia cell phones was approximately q=-p+156 million phones when the wholesale price was $p. a. If Nokia was prepared to supply q=4p-394 million phones per quarter at a wholesale price of$p, what would be the equilibrium price? b. The actual wholesale price was $105 in the fourth quarter of 2004. Estimate the projected shortage or surplus at that price.