Electricity used, measured in kilowatts hours per month, was recorded for ten homes in

a development. A scatterplot was produced and a the parabola of best fit was determined.

Quadratic Polynomial of Best Fit: y = -.00045x 2 +2.4x - 1216.1 where y is energy used in KW

hrs/month and x is the home size in square feet.

a. Using algebraic techniques we have learned, find the maximum energy used (in KW Hrs/Month)

in the development and find the square footage of a house that would use this much electricity.

Show algebraic work. Round to one decimal place.

b. Use the quadratic polynomial to estimate the electricity used in a 2100 square foot house. Round

to one decimal place. (Work optional)

c. Use the quadratic polyno mial y = -.00045x 2 +2.4x - 1216.1 together with algebra to estimate the

s quare footage of a house that uses 1600 KW Hrs/Month of electricity. That is solve the equation

1600 = -.00045x 2 +2.4x - 1216.1 Show algebraic work in solving. State your results clearly.

Round to one decimal place. (Hint: use quadratic equation.)

Home Size KW Hrs/Month

1290 1182

1350 1172

1470 1264

1600 1493

1710 1571

1840 1711

1980 1804

2230 1840

2400 1956

2930 1954