An internet provider wants to see if male and female college students spend a different amount of time online each day. In a random sample of 200 male college student shows the mean was 85 minutes with σ = 15 minutes. Another sample of 250 female college students has a mean of 81 minutes and σ = 17 minutes. Is there enough evidence to prove the claim at α = .05.

Based on sample​ data, newborn males have weights with a mean of3250.3g and a standard deviation of 726.3g. Newborn females have weights with a mean of 3061.3g and a standard deviation of 546.4g. Who has the weight that is more extreme relative to the group from which they​ came: a male who weighs 1600g or a female who weighs 1600​g? Since the z score for the male is z= ?

3. The probability of successfully navigating an asteroid field in a science fiction movie is found to be 0.01. A total of2000 spaceships attempt to navigate the field, and the number that make it through is recorded. Can thisdistribution be modelled using a normal approximation?

Consider that μ1 and μ2 are the true mean stopping distances for motorcycles at 30 mph equipped with two different sets of tires. Tire set 1 is more expensive, so we only want to buy them if there is strong evidence that there is a mean stopping distance of at least 3 ft shorter at 30 mph.  For Tire set 1, after nine tests, we get an x-bar1 of 110 ft and an s1 of 5 ft. For Tire set 2, after eight tests, we get an x-bar2 of 120 ft and an s2 of 6 ft. Assume that the distributions of stopping distances are roughly normal.  (a) Find a point estimate of μ1 – μ2.  Is the estimate biased or unbiased? (b) Find the estimated standard error the point estimate of μ1 – μ2? (c) Formulate and test the appropriate hypothesis at the α = 0.05 level.

A random sample of n1 = 20 winter days in Denver gave a sample mean pollution index x1 = 43. Previous studies show that ?1 = 11. For Englewood (a suburb of Denver), a random sample of n2 = 18 winter days gave a sample mean pollution index of x2 = 36. Previous studies show that ?2 = 15. Assume the pollution index is normally distributed in both Englewood and Denver. Do these data indicate that the mean population pollution index of Englewood is different (either way) from that of Denver in the winter? Use a 1% level of significance.   a) What is the value of the sample test statistic? (Test the difference ?1 − ?2. Round your answer to two decimal places.)b) Find (or estimate) the P-value. (Round your answer to four decimal places.)

A major credit card company is investigating whether the distribution of the number of credit cards used by its customers has changed from last year to this year. Customers are classified as using 1 card, 2 cards, or more than 2 cards. The company conducts a chi-square goodness-of-fit test to investigate whether there is a change in the distribution of number of cards used from last year to this year. The value of the chi-square test statistic was  χ2=7.82 with a corresponding p-value of 0.02. Assuming the conditions for inference were met, which of the following is the correct interpretation of this p-value?       There is a 2 percent chance that the company’s claim is correct. A There is a 2 percent chance of obtaining a chi-square value of at least 7.82. B If the null hypothesis were true, there is a 2 percent chance of obtaining a chi-square value of at least 7.82. C If the null hypothesis were true, there is a 2 percent chance that the company’s claim is…

A major credit card company is investigating whether the distribution of the number of credit cards used by its customers has changed from last year to this year. Customers are classified as using 1 card, 2 cards, or more than 2 cards. The company conducts a chi-square goodness-of-fit test to investigate whether there is a change in the distribution of number of cards used from last year to this year. The value of the chi-square test statistic was χ2=7.82χ2=7.82 with a corresponding pp-value of 0.02. Assuming the conditions for inference were met, which of the following is the correct interpretation of this pp-value?

The boiling point of 16 samples of a certain brand of hydrogenated vegetable oil used in a fryer was collected, resulting in Xbar=152.1 degrees. Assume that the distribution of melting point is normal with o=3.20. If the boiling point is different than 150 degrees, then either the oil will be too hot and will burn food or it will be too cool and will not properly cook the food. Is the sample mean significantly different from the target of 150 degrees? Use alpha=0.01 Но: H1: Define critical (rejection) region(s): Calculate the appropriate test statistic: What decision do we make? What this decision means in terms of this problem?

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6.11 Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals.Compute a 95% CI for the mean age.