1. A fruit grower sprays 200 trees with a new spray and 200 other trees with a standard spray to protect against insect damage. The following data were recorded:
|
New spray
|
Standard spray
|
|
Mean yield per tree (kg)
|
109
|
103
|
|
Variance
|
445
|
372
|
a) Obtain the p-value for testing if the new spray has significantly increasedmean yield per tree compared to the standard spray, and obtain a 95% two-sided confidence interval for the difference between mean yields.
b) Find the sample size required to obtain a 95% confidence interval having width = 1kg.