Dana Corp. uses linear regression to estimate costs. The machine hours and related costs for the last year, as well as the regression analysis results, are as follows:

Month	Maintenance Cost			Machine Hours
Jan.	$	4,450			580
Feb.		3,250			420
Mar.		3,850			500
Apr.		3,070			400
May		4,600			600
June		3,210			410
July		3,280			420
Aug.		4,720			620
Sept.		4,510			590
Oct.		4,300			570
Nov.		3,550			450
Dec.		3,410			440
Sum	$	46,200			6,000
Average	$	3,850		$	500
Average cost per hour				$	8.00
a (intercept)				$	205.82
b (coefficient)					7.2884
Standard error of the estimate					34.469
R-squared					0.99724
t-value for b					60.1050

If machine hours are 400, Aaron's manager can be approximately two-thirds confident that the range of the maintenance costs will be

Multiple Choice

• $3,060.72 to $3,181.61.

• $3,059.74 to $3,182.62.

• $3,086.71 to $3,155.65.

• $3,095.43 to $3,147.05.

• None of these answer choices are correct.