Unit 4 check

Unit 4 check: Inference for Quantitative Data: Means

10 questions from 10 lessons in Unit 4. Answer each one, and if you miss, follow the link back to where it is taught, then try again. Your score counts first tries.

Question 1 · from 4.1 · Multiple choice

The weights of eggs from a large farm are approximately normal with mean 58 grams and standard deviation 4 grams. A worker selects a random sample of 8 eggs and finds their mean weight. Which describes the sampling distribution of the sample mean weight?

Question 2 · from 4.2 · Multiple choice

A food scientist measures the sodium content of a random sample of 16 cans from a large production run of soup. The sample shows no strong skew or outliers. Which critical value should she use for a 90% confidence interval for the mean sodium content of all cans in the run?

Question 3 · from 4.3 · Multiple choice

A 95% confidence interval for the mean time students at a large school spend on homework each night, from a random sample of 50 students, is 24 minutes wide. If the sample had 200 students and the sample standard deviation came out about the same, the width would be closest to

Question 4 · from 4.4 · Multiple choice

A teacher randomly selects 12 of the 95 students in her school's robotics club and records how many minutes each one spent on the club's online forum last week. She wants to test whether the mean for all club members is more than 60 minutes. A dotplot of the 12 times is roughly symmetric with no outliers. Which condition is NOT met?

Question 5 · from 4.5 · Multiple choice

A researcher measures the reaction times of 16 randomly selected drivers twice, once when rested and once after a night of short sleep, and tests $H_{a} : μ_{d} > 0$ , where each difference is (short-sleep time minus rested time). The test statistic is $t = 2.31$ . How should the p-value be found?

Question 6 · from 4.6 · Calculate

Scores on a reading assessment have standard deviation 6 points in District 1 and 8 points in District 2, both large districts. Independent random samples of 36 students from District 1 and 32 students from District 2 are selected. Find the standard deviation of the sampling distribution of ${\overline{x}}_{1} - {\overline{x}}_{2}$ . Round to three decimal places.

Your answer

Question 7 · from 4.7 · Calculate

Independent random samples give $n_{1} = 18$ , $s_{1} = 4.2$ and $n_{2} = 22$ , $s_{2} = 5.6$ . Find the standard error of ${\overline{x}}_{1} - {\overline{x}}_{2}$ . Round to three decimal places.

Your answer

Question 8 · from 4.8 · Multiple choice

A randomized experiment compares two study apps. A 95% confidence interval for $μ_{1} - μ_{2}$ , the difference in mean quiz score (App 1 minus App 2) for students like those in the study, is (-2.3, 4.1) points. Which statement is correct?

Question 9 · from 4.9 · Multiple choice

Volunteers are randomly assigned to solve a set of puzzles either while listening to music or in silence, and the time to finish is recorded. The test will use $H_{0} : μ_{1} = μ_{2}$ , with group 1 the music group. Which is the best definition of $μ_{1}$ ?

Question 10 · from 4.10 · Multiple choice

A high school asks, "Do students who eat breakfast have a higher mean score on the state reading assessment than students who do not?" It selects independent random samples of both kinds of students from its records, and a two-sample t-test of $H_{a} : μ_{B} > μ_{N}$ gives a p-value of 0.004. At $α = 0.05$ , which answer to the question is best supported?

0 of 10 answered.