A conical tank (with vertex down) is 12 feet across the top and 18 feet deep. If water is flowing into the tank at a rate of 18 cubic feet per minute, find the rate of change of the ) depth of the water when the water is 10 feet deep. = ^2ℎ (

a. $250

b. The total cost for x month is $200 + $50 × x

c. Please see the attached graph

d. Yes, there is a proportional relationship between time and the cost of the cell phone plan

e. $350

Step-by-step explanation:

The given parameters are;

The costs to start on the cell phone cell = $200

The charge each month = $50

a. The total cost to use the cell phone plan for 1 month = Start up fee + Monthly charge = $200 + $50 = $250

b. The total cost for x month, c = $200 + $50 × x

c. Please see the attached graph

d. Yes, there is a proportional relationship between time and the cost of the cell phone plan

e. The line parallel to the line graphed that goes to the point (0, 350), is given as follows;

y = m·x + c

Where;

m = 50

y - 350 = 50 × (x - 0)

y = 50·x + 350

The startup fee is given by the total cost at x = 0, when the monthly fee is excluded, which gives;

c = 50 × 0 + 350 = 350

The startup fee for the pricing plan = $350.