Question

the standard deviation in the pressure required to open a certain valve is known to be (sigma = 1.3) psi. due to changes in the manufacturing process, the quality - control manager feels that the pressure variability has increased. (a) state the null and alternative hypotheses in words. (b) state the null and alternative hypotheses symbolically. (c) explain what it would mean to make a type i error. (d) explain what it would mean to make a type ii error. (a) state the null hypothesis in words. choose the correct answer below. a. the standard deviation in the pressure required to open any valve is 1.3 psi. b. the standard deviation in the pressure required to open any valve is 1.3 psi. c. the standard deviation in the pressure required to open a certain valve is 1.3 psi. d. the standard deviation in the pressure required to open a certain valve is greater than 1.3 psi. e. the standard deviation in the pressure required to open a certain valve is different from 1.3 psi.

Explanation:

The null hypothesis is a statement of no change or no difference. In this context, we are dealing with the standard deviation of the pressure required to open a certain valve. The null hypothesis should be about the standard deviation of the specific valve (not any valve) having the known value.

Answer:

C. The standard deviation in the pressure required to open a certain valve is 1.3 psi.