Question

please answer all question 16-20

Question 16 2 pts The population mean for a standardized test is 250. A research study with N = 30 adults from Virginia had a mean score of 260, with a 95% confidence interval of the mean reported as [248, 272]. What decision should be made based on this confidence interval? o Run the hypothesis test again o Accept the research hypothesis o Reject the null hypothesis o Fail to reject the null hypothesis Question 17 1 pts An instructor wanted to predict final exam grade from hours sleep the night before the exam. What type of graph should the instructor use to illustrate his findings? o stem-and-leaf plot o pie chart o line graph o bar graph Question 18 2 pts Assume a positive correlation is found between the number of hours students spend studying for an exam and their grade on the exam. If the regression equation for these data is calculated and the y intercept is 65, what conclusion can be drawn? o The slope of the regression line is 65 when students do not study at all. o When students do not study at all, we would predict a score of 65 on the exam. o The standard error of the estimate is low. o The regression line crosses the x-axis at a score of 65. Question 19 2 pts A distribution of means would be more likely to have compared to a distribution of raw scores. o equal standard deviation o higher standard deviation o lower variance o higher variance

Answer 1

Q16) As we are trying to test here whether the mean is 260, therefore the null and the alternative hypothesis here are given as:

Ho : = 260

$H_1: \mu \neq 260$

Now we see from the confidence interval here that the mean lies in the confidence interval [248, 272] that is 248 < Mean < 272, this means that we dont have sufficient evidence to reject the claim here that the mean is 260. Therefore we fail to reject the null hypothesis here.

Q17) As we are trying to predict a value of a variable here based on some other variable value, therefore this is a case of a scatter plot use to make the prediction after which we use the line chart to get the regression line. Therefore line graph is the correct asnwer here.

Q18) The intercept is defined as the value of dependent variable for 0 value of the independent variable. Therefore here is it is defined as the value when students do not study at all, the predicted score than get on the exam. Therefore B is the correct answer here.

Q19) The standard deviation of the mean scores is defined as the ratio of standard deviation of raw scores and the square root of the sample size. Therefore the means have a lower standard deviation always.

Therefore Lower variance is the correct answer here.