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Chapter 9: Q 104. (page 610)
You are testing against based on an SRS of
observations from a Normal population. What values of the t statistic are statistically significant at the level?
The correct option is (d)
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We want to be rich In a recent year, of first-year college students responding to a national survey identified 鈥渂eing very well-off financially鈥� as an important personal goal. A state university finds that of an SRS of of its first-year students say that this goal is important. Is there convincing evidence at the significance level that the proportion of all first-year students at this university who think being very well-off is important differs from the national value of 73%?
Significance tests A test of versus based on
a sample of size yields the standardized test statistic . Assume that the conditions for performing inference are met.
a. Find and interpret the P-value.
b. What conclusion would you make at the significance level? Would
your conclusion change if you used 伪=0.05 instead? Explain your reasoning.
c. Determine the value of p^= the sample proportion of successes.
Heavy bread? The mean weight of loaves of bread produced at the bakery where you work is supposed to be pound. You are the supervisor of quality control at the bakery, and you are concerned that new employees are producing loaves that are too light. Suppose you weigh an SRS of bread loaves and find that the mean weight is pound.
a. State appropriate hypotheses for performing a significance test. Be sure to define the parameter of interest.
b. Explain why there is some evidence for the alternative hypothesis.
c. The P-value for the test in part (a) is . Interpret the P-value.
d. What conclusion would you make at the significance level?
Fonts and reading ease Does the use of fancy type fonts slow down the reading of text on a computer screen? Adults can read four paragraphs of a certain text in the common Times New Roman font in an average time of 22 seconds. Researchers asked a random sample of 24 adults to read this text in the ornate font named Gigi. Here are their times (in seconds):
Do these data provide convincing evidence that it takes adults longer than 22 seconds, on average, to read these four paragraphs in Gigi font?
Cell-phone passwords A consumer organization suspects that less than half of parents know their child鈥檚 cell-phone password. The Pew Research Center asked a random sample of parents if they knew their child鈥檚 cell-phone password. Of the parents surveyed, reported that they knew the password. Explain why it isn鈥檛 necessary to carry out a significance test in this setting.
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