A photoconductor film is manufactured at a nominal thickness of25 mils. The product engineer wishes to increase the mean speed ofthe film, and believes that this can be achieved by reducing thethickness of the film to 20 mils. Eight samples of each filmthickness are manufactured in a pilot production process, and thefilm speed (in microjoules per square inch) is measured. For the25-mil film, the sample data result is x-bar1=1.13 and s1=0.11,while for the 20-mil film, the data yield x-bar2=1.08 and s2=0.09.Note that an increase in film speed would lower the value of theobservation in microjoules per square inch.
(a) Do the data support the claim that reducing the filmthickness increases the mean speed of the film? Use a=0.10 andassume that the two population variances are equal and theunderlying population of film speed is normally distributed. Whatis the P-value for this test? Round your answer to threedecimal places (e.g. 98.765).
The data ___support/do not support___ the claim that reducingthe film thickness increases the mean speed of the film. TheP-value is _______.
(b) Find a 95% confidence interval on the difference in the twomeans that can be used to test the claim in part (a). Round youranswers to four decimal places (e.g. 98.7654).
_______ <= mu1 - mu2 <= _______
