Quiz 7 - Quiz 9 15 minutes PDF

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Quiz 9 15 minutes...

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1 Math 10043 1.

Quiz 7

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The speeds of vehicles driving past a certain point on a highway are normally distributed with a mean of 74.8 mph and a standard deviation of 4.3 mph. If 15 vehicles driving past the point are selected at random, what is the probability that their mean speed is between 72 and 78 mph?

2. A statistics professor asked her students whether or not they were registered to vote. In a sample of 50 of her students, 35 said they were registered to vote. (a) Find the sample proportion for the students who said they were registered to vote.

(b) Find the margin of error for a 95% confidence interval for the true proportion of the professor’s students who were registered to vote.

(c) Find a 95% confidence interval estimate for the true proportion of the professor’s students who were registered to vote.

2 (d) According to a Gallup poll, about 73% of 18- to 29-year-olds said that they were registered to vote. Does the 73% figure from Gallup seem reasonable for the professor’s students? Explain.

(e) If the professor only knew the information from the Gallup poll from part (d) (73% of students said that they were registered to vote) and wanted to estimate the percentage of her students who were registered to vote within a margin of error of 4% with 95% confidence, how many students should she sample?...