Question

15) Suppose that the amount of time required to perfectly cook a waffle is known to be normally distributed, with mean of 236 seconds and variance of 5 seconds squared. (Note: I'm just making this up for the sake of this question, please don't ruin your waffles cooking them this way) What z-score would you use to find the probability that a waffle will be perfectly cooked in 236 seconds or less? (Round your answer to two decimal points)

16)Suppose you have no idea how the amount of time required to perfectly cook a pancake is distributed, so you measure the cooking time for a sample of 138 random pancakes (cooked under identical conditions) and find that the average cooking time for this sample was 90 seconds, and the sample standard deviation of the cooking times for this group of 138 pancakes was 23 seconds.

Your friend believes that the true average cooking time for pancakes is 91 secondsand wants you to use your new stats skills (and this pancake data) to test the null-hypothesis that the true mean is 91 seconds, given your observed sample mean of 90 seconds.

What is the absolute value of the t-stat is associated with this hypothesis test? (Enter only a positive number)

17) Suppose you have no idea how the amount of time required to perfectly cook a pancake is distributed, so you measure the cooking time for a sample of 141 random pancakes (cooked under identical conditions) and find that the average cooking time for this sample was 96 seconds, and the sample standard deviation of the cooking times for this group of 141 pancakes was 21 seconds.

Construct a 95% confidence interval around your estimated sample mean (using +/- 1.96 standard errors as your cutoffs). What is the value of the lower end of this confidence interval?

18)Suppose you have no idea how the amount of time required to perfectly cook a pancake is distributed, so you measure the cooking time for a sample of 128 random pancakes (cooked under identical conditions) and find that the average cooking time for this sample was 95 seconds, and the sample standard deviation of the cooking times for this group of 128 pancakes was 24 seconds.

What is the standard error for your mean cooking time estimate?

19)

Suppose you have surveyed 146 random CSUCI students and 101 random CSUN students to learn about how much time they spend looking for parking on their respective campuses.

The sample mean for CSUCI students is 14 minutes, with sample standard deviation of 4 minutes.

The sample mean for CSUN students is 16 minutes, with a sample standard deviation of 6 minutes.

Test the null-hypothesis that the true average parking time for students at both campuses is the same. What is the absolute value of the t-statistic is associated with this hypothesis? (Enter a positive number)

20)

Suppose you have surveyed 119 random CSUCI students and 149 random CSUN students to learn about how much time they spend looking for parking on their respective campuses.

The sample mean for CSUCI students is 23 minutes, with sample standard deviation of 7 minutes.

The sample mean for CSUN students is 20 minutes, with a sample standard deviation of 6 minutes.

What is the standard error of the difference in mean parking-search times?

Answer 1