Using the teacher's rating data, is there an association between native (native English speakers) and the number of credits taught? What test will you use?

If I wanted to test for association using chi-square test, whether there is an association between gender (Male or Female) and tenure-ship (tenured or not tenured), what will be my degree of freedom?

Consider a normally distributed data set with mean μ = 63.18 inches and standard deviation σ= 13.27 inches. What is the z-score when x = 91.54 inches? (To 3 decimal places)

Battery life of smartphones is of great concern to customers. A consumer group tested four brands of smartphones to determine the battery life. Samples of phones of each brand were fully charged and left to run until the battery died. The table above displays the number of hours each of the batteries lasted. What test will be be using to test the difference in means?

A room in a laboratory is only considered safe if the mean radiation level is 400 or less. When a sample of 10 radiation measurements were taken, the mean value of the radiation was 414 with a standard deviation of 17. There are concerns that mean radiation is above 414. Radiation levels in the lab are known to follow a normal distribution with standard deviation 22. We will like to conduct a hypothesis test at the 5% level of significance to determine whether there is evidence that the laboratory is unsafe.

What will be the appropriate test?

The mineral content of a particular brand of supplement pills is normally distributed with mean 490 mg and variance of 400. What is the probability that a randomly selected pill contains at least 500 mg of minerals?

The P-value for a normally distributed right-tailed test is P=0.042. Which of the following is INCORRECT ?

The time X taken by a cashier in a grocery store express lane to complete a transaction follows a normal distribution with mean 90 seconds and standard deviation 20 seconds.What is the first quartile of the distribution of X (in seconds)?

A man accused of committing a crime is taking a polygraph (lie detector) test. The polygraph is essentially testing the hypotheses

H0: The man is telling the truth vs. Ha: The man is not telling the truth.

Suppose we use a 5% level of significance. Based on the man’s responses to the questions asked, the polygraph determines a P-value of 0.08. We conclude that:

The average hourly wage at a fast-food restaurant is $5.85 with a standard deviation of $0.35. Assume that the wages are normally distributed. The probability that a selected worker earns more than $6.90 is