One Sample Z Test

If your sample mean is 10, your population average is 15, and your standard error of the mean is 10, what is your observed z value?

• 2.5

• −0.5

• −2

• 0.5

In the formula for calculating a z score, what does μ stand for?

• the obtained value

• the critical value

• the population average

• the sample average

USA Today reported that in 1992, 39% of all elementary school children claimed that when they grow up they want to do something to help other people. However, in 1995, 128 of a random sample of 317 of these same children claimed that when they grow up they want to do something to help other people. Does this information indicate that there has been an attitude change either way?

• One-Sample Z Test for a Proportion

• Two-Sample Z Test for the Difference in Proportions

• One-Sample T Test for a Mean

• Two-Sample T Test for the Difference in Means

The manufacturer of a particular brand of microwave popcorn claims that only 2 percent of its kernels of corn fail to pop. A competitor, believing that the actual percentage is larger, tests 2,000 kernels and finds that 44 failed to pop. Do these results provide sufficient evidence to support the competitor's belief?

• One-Sample Z Test for a Proportion

• One-Sample T Test for a Mean

• Two-Sample Z Test for a Proportion

• Matched-Pairs T Test for a Mean

A leading auto manufacturer claimed that a popular version of its minivan was available in the Midwest foran average price or $16,000 with a standard deviation of $800. A consumer group doubted that report andsurveyed 50 recent purchasers of the minivan to dispute the manufacturer's claim. They came up with anaverage of $16,277. Does this show that the manufacturer is making a false claim?

• One-Sample Z Test for a Mean

• Matched-Pairs T Test for a Mean

• Two-Sample T Test for the Difference in Means

• One-Sample Z Test for a Proportion

White blood cell counts are normally distributed with mean 7500 and variance 500. If a patient has taken 50 laboratory blood tests that have a mean of 6899.75 and a standard deviation of 393.44, does this give evidence that his white blood cell count is significantly different than normal?

• One-Sample T Test for a Mean

• One-Sample Z Test for a Proportion

• One-Sample Z Test for a Mean

• One-Sample T Test for a Proportion

The supervisor of a certain company claimed that the mean workday of his workers is 8.3 hours per day. A sample of 20 workers was taken and it was found out that the mean workday is 8 hours with standard deviation of 1 hour. At 0.01 level of significance, is the mean workday less than 8.3 hours?

Based on the problem, 8.3 hours is _____________.

• σ

• µ

• 𝑥̅

• 𝑠

__________________ is a random variable that is calculated from sample data and is used in a hypothesis test.

Based on the Central Limit Theorem, when the sample (n) is extremely large and the variance is unknown, what is the statistical test to be used?

• t-test

• z-test

• two-tailed test

• one-tailed

Which of the following is NOT a consideration in using z-test/statistic?

• Variance is known.

• Sample standard deviation is known.

• The population mean is less than 30.

• Population standard deviation is known.