Question

The cost of a leading liquid laundry detergent in different sizes is given below.

Size (ounces)	Cost ($)	Cost per ounce
16	3.99
32	4.79
64	5.59
200	10.99

What is the slope of the least squares (best-fit) line? (Round your answer to three decimal places.)

__________________
Interpret the slope. Choose A or B

A. As the cost of liquid laundry detergent increases by $1, the detergent size increases by this many ounces.

B. As the number of ounces increases by one, the cost of the liquid laundry detergent increases by this many dollars.   

Answer 1

The statistical software output for this problem is:

Simple linear regression results:
Dependent Variable: Cost ($)
Independent Variable: Size (ounces)
Cost ($) = 3.5617871 + 0.033374525 Size (ounces)
Sample size: 4
R (correlation coefficient) = 0.99889436
R-sq = 0.99778994
Estimate of error standard deviation: 0.16110361

Parameter estimates:

Parameter	Estimate	Std. Err.	Alternative	DF	T-Stat	P-value
Intercept	3.5617871	0.11829476	? 0	2	30.109424	0.0011
Slope	0.033374525	0.0011106632	? 0	2	30.049184	0.0011

Analysis of variance table for regression model:

Source	DF	SS	MS	F-stat	P-value
Model	1	23.435591	23.435591	902.95349	0.0011
Error	2	0.051908745	0.025954373
Total	3	23.4875

Hence,

Slope of least sqares line = 0.033

As the number of ounces increases by one, the cost of the liquid laundry detergent increases by this many dollars.

Option B is correct.