StraighterLine Macroeconomics with complete verified solutions

The students in a class are given an exam with a maximum score of 100. Their numerical scores are an example of what type of data? 80 55 60 80 75 95 90 Ans: Ratio (since a the score is given we know it is not nominal, it is not in order so it is not ordinal nor is it written in interval form) These exam scores are an example of ratio data because there is a meaningful zero point for these data, and because the ratio of two scores is meaningful. That is, a score of zero on the exam would mean that no questions were answered correctly, and a score of 90 on the exam would be 50% better than a score of 60. What is the mode of the values in the table? 80 55 60 80 75 95 90 Ans: 80 The mode is 80 because it is the most frequently-occurring value in the table. Which situation involves two statistically independent events? Ans: fair dice thrown at the same time How many different combinations of 2 students can be chosen from a class of 25, where the order of selection does not matter? Using the combination formula, n!/r!(n-r)! A researcher performs a two-tailed test of the hypothesis that a sample mean is greater than zero at the 90% confidence level. The population variance is known. What is the critical value of the z-statistic? 1.65 The z-statistic of z=1.65 would result in a confidence level of 90.1%, because the area under the normal curve between z=0 and z=1.65 corresponds an area of 0.4505. This is as close to a 90% confidence level as a table with only two decimal places for z allows. The dean at a university believes that the grade point average varies across freshman, sophomore, junior, and senior years. She takes a random sample of 25 students from each year and looks up their grades. The null hypothesis is H0: µ₁=µ₂=µ₃ If she is going to use one-way analysis of variance (ANOVA), what will her alternative hypothesis Text be? Not all of the means are equal A researcher finds a significant statistical association between aggressive behavior and poor grades among middle school students. What is one difficulty in interpreting this finding? The direction of causality is unclear. Josh wants to study the effect of a new fertilizer on tomato plants. He randomly selects a set of 20 tomato plants from his garden to receive the new fertilizer and is measuring how high they grow over the next month. How should Josh construct his study to make this a valid experimental design? Select a control group of tomato plants that will not receive any fertilizer.