Question

A photoconductor film is manufactured at a nominal thickness of 25 mils. The product engineer wishes to increase the mean speed of the film, and believes that this can be achieved by reducing the thickness of the film to 20 mils. Eight samples of each film thickness are manufactured in a pilot production process, and the film speed (in microjoules per square inch) is measured. For the 25-mil film, the sample data result is F = 1.14 and si = 0.11, while for the 20-mil film, the data yield F2 = 1.07 and s2 = 0.09. Note that an increase in film speed would lower the value of the observation in microjoules per square inch. (a) Do the data support the claim that reducing the film thickness increases the mean speed of the film? Use a = 0.10 and assume that the two population variances are equal and the underlying population of film speed is normally distributed. What is the P-value for this test? Round your answer to three decimal places (e.g. 98.765). The data the claim that reducing the film thickness increases the mean speed of the film. The P-value is (b) Find a 95% confidence interval on the difference in the two means that can be used to test the claim in part (a). Round your answers to four decimal places (e.g. 98.7654). <Mi - H2

Answer 1

1	2
1.14	1.07	mean
0.11	0.09	std. dev.
8	8	n
	14	df
	0.07000	difference (1 - 2)
	0.01010	pooled variance
	0.10050	pooled std. dev.
	0.05025	standard error of difference
	0	hypothesized difference
	1.393	t
	.093	p-value (one-tailed, upper)
	-0.0378	confidence interval 95.% lower
	0.1778	confidence interval 95.% upper
	0.10777	margin of error

The data does not supports the claim that reducing the film thickness increases the mean speed of the film. The P-value is 0.093.

b)

-0.0378 <=u1-u2<= 0.1778