Refer to the data in the file that accompanies this book named HealthClaims.xlsx (below) representing 2 years of monthly health insurance claims for a self-insured company.

Time
Year Month Period Claims
2015 1 1 $10,159
2 2 $11,175
3 3 $12,310
4 4 $12,446
5 5 $13,213
6 6 $16,412
7 7 $17,405
8 8 $14,233
9 9 $14,606
10 10 $12,969
11 11 $13,980
12 12 $14,755
2016 1 13 $12,300
2 14 $13,224
3 15 $13,606
4 16 $13,659
5 17 $16,442
6 18 $17,334
7 19 $19,605
8 20 $18,997
9 21 $15,971
10 22 $15,740
11 23 $16,919
12 24 $18,931
2017 1 25 --
2 26 --
3 27 --
4 28 --
5 29 --
6 30 --
Use regression analysis to fit a quadratic trend model to the data set.

a. What is the estimated regression function? Note: Use time periods starting with t =1.