High$-$Low Method

Luisa Crimini has been operating a beauty shop in a college town for the past $10$ years. Recently, Luisa rented space next to her shop and opened a tanning salon. She anticipated that the costs for the tanning service would primarily be fixed, but found that tanning salon costs increased with the number of appointments. Costs for this service over the past $8$ months are as follows:

Tanning

Month Appointments Total Cost

January $600$ $$1,758$

February $1,900$ $$2,110$

March $3,400$ $$2,850$

April $2,400$ $$2,500$

May $1,500$ $$1,700$

June $2,200$ $$2,285$

July $2,180$ $$2,300$

August $3,000$ $$2,610$

Required:

$1.$ Which month represents the high point? The low point?