STATISTICS 3N03

TEST #2 - 1999-10-29

 

Instructions

Aids permitted: any calculators, any tables, and one sheet of notes (8.5" x 11", one side only).

 

Questions

1. (a) You are an experimenter about to take n measurements . What can you do to ensure that ?

(b) You are a statistician and an experimenter has given you n numbers . What are all the things you can do to test the assumption that ?

(c) Write out the statement in matrix form.

2. Let and define . Find and hence find . Compare to , where .

3. A firm manufactures training weights. Because of variations in the casting process, the actual weight of a "10-kg" weight will vary according to a distribution. To be accepted, a weight must be within 100 g of the target weight.

(a) What is the probability that a given weight will be outside the acceptance limits?

(b) If 10 randomly-selected weights are tested, what is the probability that all of them will be within the acceptance limits?

(c) Could you use the normal approximation to the binomial to compute the answer to (b)? Explain.

4. Suppose you measured a temperature 10 times and found a mean of 78.56º C and a standard deviation of 2.05º C. Give a 95% confidence interval for the true mean temperature, stating any assumptions you make.


Statistics 3N03