Confidence Intervals and Sample Size

To determine the sample size needed for a survey.

To estimate the true proportion of a population.

To calculate the mean of a dataset.

To find the standard deviation of a sample.

Population mean

Sample size (n)

Sample proportion (P hat)

Critical value (Z alpha/2)

By subtracting the number of failures from the total sample size.

By dividing the number of successes by the total sample size.

By multiplying the number of successes by the total sample size.

By adding the number of successes and failures.

1.28

1.64

1.96

2.58

Using a calculator

Rounding numbers too early

Using parentheses

Checking calculations

50% is the true proportion.

50% is the sample proportion.

50% is a possible true proportion.

50% is not a possible true proportion.

To minimize the margin of error.

To maximize the sample proportion.

To ensure the sample is representative.

To reduce the survey cost.

It has no effect on sample size.

It decreases the required sample size.

It increases the required sample size.

It doubles the required sample size.

1.44

1.64

1.96

1.28

By subtracting the lower bound from the upper bound.

By averaging the upper and lower bounds.

By dividing the upper bound by the lower bound.

By multiplying the upper and lower bounds.