$10-25$ Account analysis, high$-$low. Smith Corporation wants to find an equation to estimate some of

their monthly operating costs for the operating budget for $2021.$ The following cost and other data were

gathered for $2020$:

Month

Maintenance

Costs

Machine

Hours

Health

Insurance

Number of

Employees

Shipping

Costs

Units

Shipped

January $$4,510170$ $$8,57063$ $$28,2407,060$

February $$4,473110$ $$8,57073$ $$32,9208,230$

March $$4,660239$ $$8,57089$ $$31,6007,900$

April $$4,870304$ $$8,570102$ $$25,7606,440$

May $$5,120459$ $$8,57084$ $$23,7605,940$

June $$4,745285$ $$8,57085$ $$36,9609,240$

July $$4,927338$ $$8,57088$ $$34,8008,700$

August $$4,916363$ $$8,57080$ $$33,7208,430$

September $$5,055429$ $$8,57090$ $$26,9606,740$

October $$5,226476$ $$8,570101$ $$28,4407,110$

November $$5,370500$ $$8,57091$ $$22,0005,500$

December $$4,795281$ $$8,570101$ $$38,4009,600$

$1.$ Which of the preceding costs is variable? Fixed? Mixed? Explain.

$2.$ Using the high$-$low method, determine the cost function for each cost.

$3.$ Combine the preceding information to get a monthly operating cost function for the Smith Corporation.

$4.$ Next month, Smith expects to use $350$ machine hours, have $90$ employees, and ship $8,600$ units. Estimate

the total operating cost for the month.