Confidence Interval Test Corrections

Sarah made a 95% confidence interval for the average age of students at her gym, (3.67, 10.43). What is the point estimate?

Mathematical Equivalence

ON

Match the following intervals with their Margin of Errors

• .15

• (.14, .74)

• .30

• (.56, .62)

• .06

• (.32, .62)

• .03

• (.72, .84)

• .015

• (.45, .48)

Sarah made a 95% confidence interval for the average age of students at her gym, (3.67, 10.43). What is the margin of error?

Mathematical Equivalence

ON

To decrease the size of the confidence interval we ​ (a)   the confidence level and ​ (b)   sample size

• decrease
• increase

Lucy sampled 60 people and found that the average age was 15 with a standard deviation of 2.4. What is the lower bound of a 95% confidence interval?

Mathematical Equivalence

ON

Lucy sampled 60 people and found that the average age was 15 with a standard deviation of 2.4. What is the upper bound of a 95% confidence interval?

Mathematical Equivalence

ON

Which of the following is the definition of a "point estimate?"

• The midpoint of the confidence interval

• The sample size

• The population

• The standard deviation

The amount added and subtracted to the statistic.

• Margin of error

• Statistic

• Population

• Point estimator

The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 50 batteries had a mean lifetime of 120.1 hours. Construct a 99% confidence interval for the mean lifetime of this type of battery.

• (111.2, 128.9)

• (114.53, 131.23)

• (112.52, 127.68)

• (118.43, 122.43)

In a survey of 104 students, it was found that 79 went to the homecoming game this year.

Calculate a 99% confidence interval for p.

• (.59, .79)

• (.62, .85)

• (.60, .90)

• (.65, .87)