The Helicopter Division of Aerospace Corp is studying assembly costs at its Marseilles plant. Past data indicates the labor hours per helicopter as shown in the data table. Using these data, apply simple linear regression, and examine the residual plot. Find the best fitting model using the non-linear trend line tool if necessary, calculate the estimated labour cost per helicopter when producing 13 helicopters. Round to 2 decimals.

Helicopter Assembly
Helicopter Number	Labor Hours
1	2000
2	1400
3	1238
4	1142
5	1075
6	1029
7	985
8	957