1) Use this information provided to find the unit rate, in dollars per kilowatt-hour, for each company.
Company P:
y1=$150.00, x1=1,250 Kilowatt-hours
y2=$198.00, x2=1,650 Kilowatt-hours
Unit rate: r=(y2-y1)/(x2-x1)
r=($198.00-$150.00)/(1,650 Kilowatt-hours-1,250 Kilowatt-hours)
r=($48.00)/(400 Kilowatt-hours)
r=$0.12/Kilowatt-hour
The unit rate of Company P is 0.12 dollars per kilowatt-hour.
Company M
y=0.15x
This is a linear equation of the form y=mx+b, where m is the unit rate: r=m. In this case r=m=0.15. Then the unit rate of Company M is 0.15 dollars per kilowatt-hour.
2) Find the total cost, in dollars, of buying 2,375 kilowatt-hours of electricity from the least espensive company.
The least expensive company is that with the lowest unit rate, in this case Company P. The total cost in dollars (y) for Company P is:
y=mx+b, when x=0, y=0, then b=0
y=mx, m=r=0.12
y=0.12x
x=2,375 kilowatt-hours
y=$0.12/kilowatt-hour (2,375 kilowatt-hours)
y=$285.00
The total cost of buying 2,375 kilowatt-hours of electricity from the least expensive company is $285.00
