Question

1. You wish to test the following claim (HaHa) at a significance level of α=0.01α=0.01.

      H0:μ1≥μ2H0:μ1≥μ2
      Ha:μ1<μ2Ha:μ1<μ2

You believe both populations are normally distributed, but you do not know the standard deviations for either.

You obtain a sample of size n1=13n1=13 with a mean of M1=69.7M1=69.7 and a standard deviation of SD1=6.7SD1=6.7 from the first population. You obtain a sample of size n2=14n2=14 with a mean of M2=85.5M2=85.5 and a standard deviation of SD2=15.9SD2=15.9 from the second population.

test statistic =
	[three decimal accuracy]
p-value =
	[three decimal accuracy]

The p-value is...

• less than (or equal to) αα
• greater than αα

This test statistic leads to a decision to...

• reject the null hypothesis
• fail to reject the null hypothesis

As such, the final conclusion is that...

• There is sufficient sample evidence to support the claim that the first population mean is less than the second population mean.
• There is not sufficient sample evidence to support the claim that the first population mean is less than the second population mean.

2. "Durable press" cotton fabrics are treated to improve their recovery from wrinkles after washing. "Wrinkle recovery angle" measures how well a fabric recovers from wrinkles. Higher is better. Here are data on the wrinkle recovery angle (in degrees) for the same fabric specimens discussed in the previous exercise:

Permafresh	Hylite
13	17
14	14
12	16
10	20
16	18
11
15

A manufacturer wants to know how large is the difference in mean wrinkle recovery angle.

Give a 95% confidence interval for the difference in mean wrinkle recovery angle:

(  ,	)
[three decimal accuracy]	[three decimal accuracy]

Answer 1