AP Statistics Inference Review

Proportion

100

A statistics question requires a significance test with null hypothesis Ho: p = 0.3, where p is a population proportion. Two students, Juan and Tamara, both do the question, and they both calculate the correct positive value of the z-statistic. However, Juan performs a one-tailed test (using the alternative hypothesis Ha: p > 0.3), and Tamara performs a two-tailed test (using the alternative hypothesis Ha: p not equal to 0.3). Given that both students are correct in their work, which of the following is NOT possible? A) Both students reject the null hypothesis at the 0.05 significance level. B) Both students fail to reject the null hypothesis at eh 0.05 significance level. C) Juan rejects the null hypothesis at the 0.05 significance level and Tamara fails to reject the null hypothesis at the 0.05 significance level. D) Juan fails to reject the null hypothesis at the 0.05 significance level and Tamara rejects the null hypothesis at the 0.05 significance level. E) Juan fails to reject the null hypothesis at the 0.01 significance level and Tamara rejects the null hypothesis at the 0.05 significance level.

What is D?

Means

100

An article describes a t-test of Ho: mu = 20 versus Ha: mu > 20, and the value of the test statistic is given to be 1.58. The sample size is not given in the article, but is known to be between 5 and 30 inclusive. Assuming that all the conditions for inference are met, the p-value for the test would be A) less than 0.01 B) between 0.01 and 0.05 C) between 0.05 and 0.1 D) between 0.1 and 0.2 E) greater than 0.2

What is C?

Linear Regression

100

The department of transportation for a particular state kept records of the number of new cars sold (x) and the number of used cars sold (y) for each month last year. Some computer output from regression analysis of these data is shown below Dependent Variable: Number of used cars sold Predictor Coef St Dev T P Constant 32971 9656 3.41 0.007 New_Cars 0.8566 0.4593 1.86 0.092 S= 5418.57 R-Sq = 25.8% R-Sq (adj) = 18.4% Treating the twelve months last year as a random sample of all months, and assuming that the other conditions for inference are met, at what level of significance do last year's results provide evidence of a non-zero slope int he population regression line of y on x? A) At the 0.01 level B) At the 0.05 level, but not at the 0.01 level C) At the 0.1 level, but not at the 0.05 level D) At the 0.05 level, but not at the 0.1 level E) Not at any reasonable significance level

What is C?

All Inference

200

It is estimated that for the people in a large community, the standard deviation of the daily calorie intake is 245. Assuming that this standard deviation is correct, how large a random sample of people from the community would be necessary in order to estimate the mean daily calorie intake to within 30 calories with 95% confidence? A) 17 B) 131 C) 257 D) 308 E) 3922

What is C?