STATISTICS 2MB3

TEST #3 * 2005-03-23

Instructions

The duration of the test is 1 hour.

Any calculators, photocopies of the Tables from the textbook,
and one sheet of notes (8.5" x 11", one side only) are permitted.

Question 1

 

You are manufacturing an auto part that is supposed to weigh 2.5 kg; however, as long as the weight is between 2.4 and 2.6 kg it will be within specifications. Your weigh scale is unbiased but has a standard deviation of 0.2 kg. If you weigh a part 4 times independently and do a two-sided 5% test, show that the probability of accepting a part that does not meet specifications could be as high as 83%. If you wanted to reduce this probability to 10%, how many times would you have to weigh the part?

Question 2

The following data give energy intake and expenditure in MJ/day for 7 soccer players. Give a P-value to test whether there is a significant difference between intake and expenditure. State your assumptions and your conclusions. Where possible, test your assumptions. Give an appropriate graph.

 

Player:                         1          2          3          4          5          6          7

Expenditure:                14.4     12.1     14.3     14.2     15.2     15.5     17.8

Intake:                         14.6     9.2       11.8     11.6     12.7     15.0     16.3

Question 3

Analyse the data of Question 2 using a non-parametric test. State your assumptions and your conclusions.

Question 4

The following data give airborne bacteria count (colonies/ft3) for samples from 8 carpeted hospital rooms and 8 uncarpeted hospital rooms. Does there appear to be a difference in the true average bacteria counts between carpeted and uncarpeted rooms? Support your conclusion with a P-value. State your assumptions and your conclusions. Where possible, test your assumptions. Give an appropriate graph.

 

Carpeted:        11.8     8.2       7.1       13.0     10.8     10.1     14.6     14.0

Uncarpeted:    12.1     8.3       3.8       7.2       12.0     11.1     10.1     13.7