Statistics Problems
posted by Lisa .
The bank sets up an experiment to test the effectiveness of the DVD. The mail it out to a random sample of delinquent customers and keep track of how many actually do contact the bank to arrange payments. The bank's statistician calculates a pvalue (probabilityvalue) of 0.003.
1. What does this pvalue suggest about the effectiveness of the DVD?
A) This is low pvalue which leads us to reject the null hypothesis and conclude that the DVD is more effective than sending a letter.
B) This is low pvalue which leads us to reject the null hypothesis and we cannot conclude that the DVD is more effective than sending a letter.
C) This is not a low pvalue so we fail to reject the null hypothesis and conclude that the DVD is more effective than sending a letter.
D) This is not a low pvalue so we reject the null hypothesis and conclude that the DVD is more effective than sending a letter.
E) The pvalue is not helpful in making a decision.
2. What additional information might be helpful in making the decision about the effectiveness of the DVD?
A) The results are very clear so no additional information is needed.
B) A confidence interval would be helpful since we can only state that the proportion of delinquent customers who pay after getting the DVD is greater than 30%.
C) The bank statistician should recalculate the pvalue since it is probably incorrect.
D) A confidence interval would be helpful since we can only state that the proportion of delinquent customers who pay after getting the DVD is less than 30%.

A market sells potatoes whose weights are normally distributed with mean 65 grams and standard deviation 15 grams.
(i) Find the probability that a randomly chosen potato weighs between 40 grams and 80 grams.
The market sells potatoes weighing more than 80 grams separately packaged. Potatoes weighing between 80 grams and L grams are labeled large and potatoes weighing over L grams are labeled as extralarge.
(ii) Given that a randomly chosen potato is twice as likely to be large as extralarge, calculate the value of L. A market sells potatoes whose weights are normally distributed with mean 65 grams and standard deviation 15 grams. 
i) 0.7937
ii) .8