8.2 confidence interval for means

Question 1

confidence interval for means using ti-84 when sigma is unknown

Question 2

assumptions for constructing a confidence interval for mean when standard deviation is unknown

Answer 2

1. we have a simple random sample

2. the sample size is large (n>30), or the population is approximately normal

Question 3

when sample size n is less than or equal to 30

Answer 3

check to determine whether the sample comes form a population that is approximately normal

Question 4

a population is approximately normal when

Answer 4

no outliers and the sample is not strongly skewed on a dot plot or boxplot, now you can construct a confidence interval using Student’s t distribution

Question 5

confidence interval on ti-84 plus

Answer 5

the Tinterval command is used when given mean and standard deviation is unknown. its found is STAT then TESTS

Question 6

the relationship between confidence level and margin of error

Answer 6

we increase the critical value when we make a more confident interval, which ultimately increases margin of error 70% is low, 99.7% is too high, 95% is where its at thats why we use it. it is the success rate of overall, not for any particular interval