In: Statistics and Probability
STOP AND READ THIS PART!! - please DO NOT answer the full question. PLEASE just explain why you would use the "pooled variances" over the method that uses degrees of freedom. please explain the differences and when you would use one over the other
READ ABOVE^^ -- A cigarette manufacturer is experimenting with two new filters for its cigarettes. Filter I is cheaper to make than Filter II and will be used unless there is statistical evidence that Filter II is more effective than Filter I. To compare the two filters, 25 cigarettes were made using each type of filter. The cigarettes were mechanically smoked and the amount (in milligrams) of trapped tar and nicotine recorded with the following results:
Filter I |
Filter II |
|
Mean |
1.10 |
1.13 |
Variance |
.05 |
.07 |
Assume the amounts of trapped tar and nicotine for cigarettes made with both filters are normally distributed with common variances. At a 5% significance level, which filter do you think the manufacturer should choose?