1.Solve:

A plumber's total bill A can be calculated using the formula A= RT + M, where R is his hourly rate, T is the total labor time in hours, and M is the cost of materials. A plumber bids a particular job at $2830. If materials amount to $1195, and his hourly rate is $60 per hour, how many hours should the job take for the estimate to be accurate?

2.A. The fire damage potential D of a forest is given by the formula D = 2A + 4., where A is the average age (in years) of the brush in the forest. If D = 13, find the average age of the brush.

b. The pressure P (in pounds per square inch or psi) on a submerged body in wastewater is given by P = 0.520D + 14.7, where D is the depth in feet. At what depth is the pressure 22.0 psi? The pressure is 22.0 psi at the depth of approximately ___ ft.

3. a. The ACH (air changes per hour) of a house is a measure of its airtightness. The formular for

ACH is ACH = 60L/V, where L is the air leakage in cubic feet per minute (cfm), and V is the

volume of the house in cubic feet. What is the maximum amount of air leakage that would

result in an ACH of no more than 1.75?

b. A salesperson has a goal of averaging $2500 worth of sales per day. During the first four

days of a week, she has achieved the following daily totals: $1860, $2228, $780, and.

$3448. What amount of sales does she need on the fifth day in order to achieve her goal

for the week?

4. Physical fitness experts sometimes use the following formula to approximate the maximum target heart rate R during exercise based on a person's age A. R = -0.8A + 176. At what age should the heart rate during exercise not exceed 153 beats per minute?