Homework Questions

Section 8.3 Estimating a Population Mean

One-Sample Z Interval for a Population Mean 𝑥 ± 𝑧 ∗ 𝜎 𝑛 As long as the Random, Normal, and Independent conditions are met…This is your confidence interval! We use this when we know 𝜎

Choosing a Sample Size Now that we know 𝜎… 𝑧 ∗ 𝜎 𝑛 ≤𝑀𝐸 𝑧 ∗ 𝜎 𝑛 ≤𝑀𝐸 Ex: Obtaining monkeys is time-consuming and expensive, so researchers want to know the minimum number of monkeys needed to generate a satisfactory estimate of cholesterol levels for a study. They want their estimate to be within 1 mg/dl of the true value of 𝜇 at a 95% confidence interval.

When 𝜎 is unknown…T distributions

When 𝜎 is unknown…T distributions 𝑡= 𝑥 −𝜇 𝑠 𝑥 𝑛 𝑑𝑓=𝑛−1

One-Sample t interval for a Population Mean 𝑥 ± 𝑡 ∗ 𝑠 𝑥 𝑛 Use when the population is Normal or the sample size is large enough (𝑛≥30) and the population is at least 10 times the sample size.

T procedures: The Normal Condition Sample size less than 30 – use t if the data appear close to Normal (roughly symmetric, single peak, no outliers). Do not use otherwise. Large Samples – t can be used even for clearly skewed distributions

#63

Homework #2 Pg 518 (63, 67-70, 72-78)