Chapter 12: Confidence Intervals. Flashcards
1
Q
What is the formula we need to remember for a confidence interval for the population mean?
A
x̄ ± z (σ/√n).
2
Q
How do we find the z-value for a Confidence Interval?
On the Calculator.
A
Stats –> DIST –> NORM –> InvN. We select the Central Tail, set our Area as the Confidence Interval and Select σ=1 and μ=0.
We only need the positive value.
3
Q
What setting on the calculator do we need to use for Confidence Intervals?
A
Stats –> INTR –> Z –> 1-sample.
4
Q
When can a normal distribution be used for determining a confidence interval?
A
When ‘n’ is large. (n≥30).
