The following data represent petal lengths (in cm) for independent random samples of two species of iris.
petal length (in cm) of iris virginica: x₁; n₁ = 35
5.0 5.8 6.2 6.1 5.1 5.5 5.3 5.5 6.9 5.0 4.9 6.0 4.8 6.1 5.6 5.1
5.6 4.8 5.4 5.1 5.1 5.9 5.2 5.7 5.4 4.5 6.4 5.3 5.5 6.7 5.7 4.9
4.8 5.7 5.1
petal length (in cm) of iris setosa: x₂; n₂ = 38
1.6 1.9 1.4 1.5 1.5 1.6 1.4 1.1 1.2 1.4 1.7 1.0 1.7 1.9 1.6 1.4
1.5 1.4 1.2 1.3 1.5 1.3 1.6 1.9 1.4 1.6 1.5 1.4 1.6 1.2 1.9 1.5
1.6 1.4 1.3 1.7 1.5 1.7
(a) use a calculator with mean and standard deviation keys to calculate x₁, s₁, x₂, and s₂. (round your answers to two decimal places.)
x₁ =
s₁ =
x₂ =
s₂ =
(b) let μ₁ be the population mean for x₁ and let μ₂ be the population mean for x₂. find a 99% confidence interval for μ₁ − μ₂. (round your answers to two decimal places.)
lower limit
upper limit