Can brainwaves be used to measure job aptitude? During the 1980s, a psychologist tried to use brainwave measurements to identify Navy recruits who are good at using a rifle. Several times each year, batches of data were analysed. Each batch of data compared various brainwave measurements with rifle-shooting performance scores for a group of recruits. The psychologist was looking for evidence of a relationship between brainwave measures and shooting skill. During 1990, he analysed 34 of these batches. In 32 of those batches, there was no evidence of association, but the other two batches were statistically significant (at level of significance α = 0.05) in demonstrating a relationship between brainwaves and shooting skill. Based on this, which of the following is true?

Suppose we are testing the null hypothesis Ho: μ = 20 against Ha: μ ≠ 20. Suppose our population is Normal with standard deviation 6. A random sample of nine (9) observations are drawn from the population, and we find the sample mean of these observations is 17. The P-value is closest to

[Hint: firstly find the test statistic, then use an appropriate statistical table and consider the nature of the alternative hypothesis]

A snack food producer produces small bags of peanuts labelled as containing 15 grams. The actual weight of peanuts packaged in individual bags is Normally distributed with mean μ and standard deviation σ = 0.4 grams.  As part of quality control, n bags are selected randomly and their contents are weighed. The hypotheses of interest are Ho: μ = 15 grams, Ha: μ ≠ 15 grams.

A psychologist administers a test of reflex times to men and women. In the study, the reaction speed to an electrical shock stimulus was measured for a sample of men and for a sample of women. The researcher thinks there may be a difference between men and women in this response. Let \mu(M) be the average reaction speed for all men. Let \mu(W) be the average reaction time for all women. 

The appropriate null and alternative hypotheses relevant to this example are

A psychologist administers a test of reflex times to men and women. In the study, the reaction speed to an electrical shock stimulus was measured for a sample of men and for a sample of women. The researcher thinks there may be a difference between men and women in this response.  Let \mu(M) be the average reaction speed for all men. Let \mu(W) be the average reaction time for all women. Which of the following is the null hypothesis of interest in this study?

Which of the following statements is correct regarding the chart above?