Thread: Hpothesis testing.

1. The viscosity of a liquid detergent is supposed to average 800 centistokes at 25C. A random sample of 16 batches of detergent is collected, and the average viscosity is 812. Suppose we know that the standard deviation of viscosity is = 25 centistokes.

(a) State the hypotheses that should be tested.

(b) Test these hypotheses using = 0.05. What are your conclusions?


(d) Find a 95 percent confidence interval on the mean

Any help would be great!
Thanks in advance!

Originally Posted by Mathtroubles

1. The viscosity of a liquid detergent is supposed to average 800 centistokes at 25C. A random sample of 16 batches of detergent is collected, and the average viscosity is 812. Suppose we know that the standard deviation of viscosity is = 25 centistokes.

(a) State the hypotheses that should be tested.

(b) Test these hypotheses using = 0.05. What are your conclusions?


(d) Find a 95 percent confidence interval on the mean

Any help would be great!
Thanks in advance!

H0: viscosity = 800.
H1: viscosity 800

Apply two-tailed z-test since the population sd is known.

If you need more help, please review the releavnt theory and examples in your class notes and textbook first and then say where you're stuck (if you still need help after doing that).