In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.
If you're seeing this message, it means we're having trouble loading external resources on our website. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. From WikiEducator Use the following quiz questions to check your understanding of random variables. Note that as soon as you have indicated your response, the question is scored and feedback is provided. As feedback is provided for each option, you may find it useful to try all of the responses (both correct and incorrect) to read the feedback, as a way to better understand the concept. Sampling distributions of a sample mean
The mean and sd of [math]\bar{x}[/math]
In an article in the Journal of American Pediatric Health researchers claim that the weights of healthy babies born in the United States form a distribution that is nearly Normal with an average weight of 7.25 pounds and standard deviation of 1.75 pounds.[1] Suppose a researcher selects 50 random samples with 30 newborns in each sample.
Central Limit Theorem
Central Limit Theorem
In 2009 the mean annual salary for teachers in the US was $49,720 with a standard deviation of $7200. The distribution is strongly skewed to the right.
Central Limit Theorem
In 2009 the mean annual salary for teachers in the US was $49,720 with a standard deviation of $7200. The distribution is strongly skewed to the right. What is the probability that the mean annual salary of a random sample of 65 US teachers is less than $48,000? Let's walk through the computations required to calculate this probability.
Central Limit Theorem
In 2011, scores on the critical reading portion of the SAT (SAT-CR) were approximately Normally distributed with mean μ = 496 and standard deviation σ = 114.
Sampling distributions for counts and proportions
The mean and sd of [math]\hat{p}[/math]
The mean and sd of [math]\hat{p}[/math]
According to the National Student Clearinghouse Research Center, 45 percent of all students who finished a four-year degree in 2010-11 had previously enrolled at a two-year college.[5]
The mean and sd of [math]\hat{p}[/math]
According to the National Student Clearinghouse Research Center, 45 percent of all students who finished a four-year degree in 2010-11 had previously enrolled at a two-year college.[6]
Understanding the sampling distribution of [math]\hat{p}[/math]
The test specifications for a math test require that 20% of the test questions relate to geometry.
Using Normal distribution calculations with the sampling distribution of [math]\hat{p}[/math]
The National Institute of Mental Health reports that approximately 10 percent of American adults suffer from depression or a depressive illness.[7] A random sample of 210 American adults is obtained.
Notes |