A sample of 27 blue M&Ms has a mean weight of 0.8560 grams. Assume that is known to be 0.0565 g. Consider a hypothesis test that uses a 0.05 significance level to test the claim that the mean weight of all M&Ms is equal to 0.8535 grams (the weight necessary so that bags of M&Ms have the weight printed on the package).

Question

A sample of 27 blue M&Ms has a mean weight of 0.8560 grams. Assume that   is known to be 0.0565 g. Consider a hypothesis test that uses a 0.05 significance level to test the claim that the mean weight of all M&Ms is equal to 0.8535 grams (the weight necessary so that bags of M&Ms have the weight printed on the package).

a)What is the test statistic? 
b)What is the critical value.
c)What is the P-value? 
d)What is the conclusion about the null hypothesis (reject, fail to reject)? 
e)Give the final conclusion in simple non-technical terms.

PsyDAG · Answer

To get P = .05, Ho needs to have μ ± 1.96 SD, Reject Ho, if value is outside that range.

P is determined by Z score = (X-μ)/SD. Look up value in "area under normal distribution" in back of your stats text.

Is "that" your SD?

I hope this helps. If not, repost with more questions. Thanks for asking.