A random sample of eighty-five students in Melbourne high schools takes a course designed to improve ATAR scores. Based on these students, a 90% confidence interval for the mean improvement in ATAR scores from this course for all Melbourne high school students is computed as (72.3, 91.4) points. We may conclude that

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A researcher selects a random sample of size n and calculate a 95% confidence interval for a population mean \mu. The interval

A researcher is conducting a study on the eating habits of university students. Instead of using a random sample, the researcher distributes the survey only during a morning lecture series. Which of the following best describes the issue with this sampling method?

The incomes in a certain large population of college teachers have a normal distribution with mean $75,000 and standard deviation $10,000. Four teachers are selected at random from this population to serve on a committee. What is the probability that their average salary is less than $65,000?

[Hint: firstly consider the standardised z-statistic for the sample average]

The incomes in a certain large population of college teachers have a normal distribution with mean $75,000 and standard deviation $10,000. Four teachers are selected at random from this population to serve on a committee. What is the standardised score (test statistic) for an average salary found to be $65,000 by this sample?

The number of column inches of classified advertisements appearing on Mondays in a certain daily newspaper has mean 320 inches and standard deviation 30 inches. Suppose that the results for 100 consecutive Mondays can be regarded as a random sample and let

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Suppose you're in a class of 30 students. The instructor takes a simple random sample of five students and observes their ages. Imagine all of the different samples possible (there are 142,506 such samples possible!). Let

The average age of residents in a large residential retirement community is 69 years with standard deviation 5.8 years. A simple random sample of 100 residents is to be selected, and the sample mean age of these residents is to be computed.

We know the sample mean has approximately a normal distribution because of

Given below are three(3) different plots of the same data showing how the amount of heat radiation transferred from an object changes with the temperature of the object.  Note that the scales used for the x and y axes are different. 

Which of the following statements is the most correct about the relationship between heat radiation and the temperature of this body. Base this on just the observation of the following plots ("imagine" the corresponding residual plots).