Math 180 (Business Calculus)

Test #3 Summer 2021 *Show all relevant works for full credit

8.(a)A rock thrown into a still pond causes a circular ripple.If the radius of the ripple is increasing by 2 feet per second howfastis he area changing when the radius is 10 feet?(Areaof acircle=r2)

(b).A sphericalbasket ballis deflating. If the radius is decreasing at 2millimeters per second,how fast is the volume changing when the radius is 10 millimeters.(Volumeof a sphere=4(3)

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9(a)Ifan object moves along the y-axis (scale in feet) so that it is at

Y =8x2-4x + 1at time x seconds

Find the instantaneous velocity function, then evaluate the velocity at time x= 4 seconds.

9(b)AtFord Motors assembly, a new employee,on the average is , is able to assemble

N(t) = 10(1- e-0.4t) units after t day oftraining.

What is the rate of learning after 3 days?

10(a) A model for the average income perhouseholdbeforetaxes are paid isf(t) = 1,900t +22,500 wheretis years since 1990, find the percentage rate of change of household income in 2020 . Round your answer to the hundredths.

10(b)Theprice -demand equation for home delivered large pizzas is

p = 38.2 -0.002x

wherexis the number of pizzasdelivered weekly. The current price of one pizzais$21. In order to generate additional revenue from the sales of large pizza, will you recommend an increase or decrease inprice?Explain