Confidence Interval
Find the Confidence Interval for 90%
1.65
What are the two types of limits in this chapter
Lower and Upper Limits
If the sample is 30 and we known the standard deviation, what test do we use?
Z-test
Are the best point of estimates and the sample mean the same?
Yes
How do you find the degrees of freedom?
N-1
Find the Confidence Interval for 95%
1.96
Do we need to know the confidence interval to find the limits?
Yes
If the sample is 30 and we don't known the standard deviation, what test do we use?
T-test
What is the formula for the estimate of the population mean?
N=(z1-a/2*SD/E)2
If a sample is 80 with a mean of 400 and a SD of 40. What is the degrees of freedom?
79
Find the Confidence Interval for 94%
1.88
What is the formal for Limits?
If the sample is 15 and we don't known the standard deviation, what test do we use?
T-test
What does E stand for in the formula for estimates of population mean
Maximum error of estimate
Consider a t distribution with 20 degrees of freedom. Compute P(-1.10<t<1.10).
.716
Find the Confidence Interval for 98%
2.326
The mean of a recent study of daily coffee consumption is 450 with a standard deviation of 50. With a sample of 80 find the Lower and Upper limits of those with a 90% confidence interval.
LL:440.7
UL:459.2
What test do we use when comparing results?
Chi-square test
Using 780 as the SD with a 99% confident, find the estimate that is within 100 of mean?
404.97
Consider a t distribution with 27 degrees of freedom. Compute P(t<1.18).
.876
Find the Confidence Interval for 99%
2.58
The mean of a recent study of daily coffee consumption is 80 with a standard deviation of 20. With a sample of 60 find the Lower and Upper limits of those with a 95% confidence interval.
LL:74.94
UL:85.06
What test do we use when comparing variances of two samples?
F-test
Using 880 as the SD with a 95% confident, find the estimate that is within 200 of mean?
74.37
Consider a t distribution with 26 degrees of freedom. Compute P(-c<t<c)=.90.
1.706