8.04 t-distribution and Small Samples

Find the value of z_c for a 90% confidence interval.

• -1.96 
• 1.645
• 1.440
• -1.598

Tags

CCSS.HSS.ID.A.4

A research company wants to estimate what percent of the population likes oatmeal.  They want the confidence level to be 95%.  The company gets 325 people to sign up for the survey, but on the day that the survey is issued, only 250 people show up and take the survey.  What happens to the confidence interval?

• It gets larger

• It gets smaller

• It stays the same

• Too little information given

Tags

CCSS.HSS.IC.B.4

True or False:

The more confident you want to be, the smaller your confidence interval will be.

• True

• False

Tags

CCSS.HSS.IC.B.4

Tags

CCSS.HSS.IC.B.4

A __________ gives an interval of plausible values for the _____________. 

• confidence interval, statistic
• point estimate, parameter
• point estimate, statistic
• confidence interval, parameter

Tags

CCSS.HSS.IC.B.4

What is z_c for a 99% confidence interval? 

• -2.58

• 1.96

• -1.64

• 2.58

Tags

CCSS.HSS.ID.A.4

What critical value t_c is used in constructing a 99% confidence interval

based on n = 12 randomly selected observations. 

• 3.106

• 3.055

• 2.58

• 1.96

Tags

CCSS.HSS.ID.A.4

If the population standard deviation σ is known,

always use _____

even if the sample size is "small".

• z_c

• t_c

Tags

CCSS.HSS.ID.A.4

In this unit, the abbreviation

"df"

stands for ___________.

• doughnut filling

• degrees of freedom

• don't fail

• dragonfly

To find the degrees of freedom,

• add one to the sample size

• subtract one from the sample size

• subtract the sample size from 1

• square root the sample size