SOLUTION: Hi, please help me solve this. Thank you and have a good day. A homeowner has kept records of the average monthly electric bill for 4 yrs. Year |Amount ($) 1

Algebra ->  Sequences-and-series -> SOLUTION: Hi, please help me solve this. Thank you and have a good day. A homeowner has kept records of the average monthly electric bill for 4 yrs. Year |Amount ($) 1       Log On


   

Question 1062406: Hi, please help me solve this. Thank you and have a good day.
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 by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Here is the differences
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[ 2 minus 1 ] = +5.4+
[ 3 minus 2 ] = +5.4+
[ 4 minus 3 ] = +5.4+
so, it's an arithmetic progression
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So, if year number 1 has average bill
+102.6+, then
Let +n+ = year number
Let +A+ = average monthly bill for
year number +n+
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+A+=+5.4n+%2B+102.6+-+5.4+
+A+=+5.4n+%2B+97.2+
Now if I start with +n+=+1+, I get
+A+=+106.2+
------------------------------------
Average monthly bill for year 6 is
+A+=+5.4%2A6+%2B+97.2+
+A+=+32.4+%2B+97.2+
+A+=+129.6+
$129.60