The cost of calling Raymond's friend in Singapore is \( \$ 3.00 \) plus \( \$ 0.40 \) per minute. The cost as a function of time is shown in the graph. Write an equation that represents the cost as a function of the number of minutes. Identify the slope and \( y \)-intercept and describe their meanings. Find the cost of a 20 -minute call.

Linda deposits \( \$ 90,000 \) into an account that pays \( 4 \% \) interest per year, compounded annually, Bob deposits \( \$ 90,000 \) into an account that also pays \( 4 \% \) per year. But it is simple interest. Find the interest Linda and Bob earn during each of the first three years. Then decide who earns more interest for each year, Assume there are no withdrawals and no additional deposits.

4. The amount of temperature rise in a concrete mass depends upon numerous variables including cement fineness and composition, ambient temperatures, mixture proportions, heat transfer from the concrete to its surroundings, and other factors. Heat gain of hydrating cement in concrete can be reduced by adding which of the following as a partial replacement for portland cement in the concrete mixture? Chemical admixtures - Pozzolans - Slags Any of a, b, or c above

The sales in thousands of a new type of product are given by \( \mathrm{S}(\mathrm{t})=240-80 e^{-0.4 \mathrm{t}} \), where t represents time in years. Find the rate of change of sales at the time when \( \mathrm{t}=8 \). Round to the nearest tenth.

Hallar la ecuación de la hipérbola que tiene focos en \( (1,-\sqrt{26}) \) y \( (1, \sqrt{26}) \) y asintotas en \( y=\frac{1}{5} x-\frac{1}{5} \) y \( y=-\frac{1}{5} x+\frac{1}{5} \)

Multiply. \[ \sqrt{-25} \cdot \sqrt{-4} \]