3

3. It is desired to determine whether there is less variability in the silver plating done by Company 1 than in that done by Company 2. If independent random samples of size 13 of the two companies? work yield s1 = 0.062 mil and s2 = 0.035 mil, test the null hypothesis ?sigma?1squared = ?sigma?2squared against the alternative hypothesis ?sigma?1squared >?sigma?2squared at the 0.05 level of significance.

4. Apples can be stored in various ways. Four different kinds of storage condition were tested, and the time before spoilage in (months) was recorded as in the table below.
a) By looking at the data, make a judgment about the effect of storage conditions on the response variable.
b) Perform an analysis of variance, and test at the 0.10 level for a significant difference associated with storage conditions.
Storage Replicate
Condition 1 2 3
A 7 8 7
B 3 3 5
C 3 4 3
D 9 7 10