Arithmetic Sequence

Question

A homeowner has kept records of the average monthly electric bill for 4 yrs.

Year        Amount ($)
  1              102.60

  2              108.00

  3              113.40

  4              118.80

a. Do the average monthly electric bills follow an arithmetic progression?
b. Write an expression for the nth term of the sequence.
c. Predict the average monthly bill for year 6 if this trend continues.

Answer 1

a)

 

Yes it does.  The common difference if 5.40.

 

 

b)

 

C_n = 102.60 + 5.40(n - 1)

 

where:

n = year

C_n = amount for after a certain year

 

 

c)

 

Evaluate C₆.

 

C₆ = 102.60 + 5.40(6 - 1)