Exam 9: Small Sample Inferences for Normal Populations

Find a 98% confidence interval for on n = 25 and s = 0.425. Round your answer to two decimal places.

The following data set shows the ages of 16 factory workers chosen at random. Find a 90% confidence interval for based on these data. Round your answers to three decimal places.

The following data set shows the ages of 16 factory workers chosen at random. Based on these data, a 90% confidence interval for is (22.754, 12.262). The workers supervisor claims that . Do the data provide strong evidence that the workers population standard deviation is smaller than 18? Test with $\alpha$ =0.05.

Refer to the following data set. A) Obtain a 95% confidence interval for . Round your answer to three decimal places. B) Obtain a 95% confidence interval for . Round your answer to two decimal places.

Consider the statistics about the lifetime of laptop L.C.D.s. Is the population mean lifetime of all laptop L.C.D.s contained in this interval?

Using the table for the distributions, find the upper 1% point when d.f. = 16. Round your answer to two decimal places.

A student, wishing to document a slow internet, observes the time , in minutes, that it takes to download a web page. The times for five pages are 1 5 3 1 5 Let µ =population mean time in minutes. (a) Obtain a 97 % confidence interval for µ. (b) Does your 97 % confidence interval cover µ. Explain. (c) When a large number of these 97 % intervals are calculated, from data collected on different occasions, explain the reason you are 97% confident that any one of them covers µ.

The weights from a random sample of 16 adult golden doodle dogs have mean 66.4 pounds and standard deviation 4.8 pounds. As- sume that the weights of the dogs have a normal distribution. Let µ =population mean number of times. (a) Obtain a 95 % confidence interval for the population mean µ. (b) Does your interval cover µ? Explain. (c) When a large number of these 95 % intervals are calculated, from data collected on different occasions, explain the reason you are 95% confident that any particular one of them covers µ.

The possible scores in a mathematics placement test are in the range 0 - 50. Recorded here are the scores obtained by eight students. A) Construct a 95% confidence interval for the population mean scoreμ . Round your answer to one decimal place. B) If you were to test H₀: μ=30 versus H₁: μ≠30 at α=0.05, what would you conclude from your result in part A. Answer "Rejected" or "not rejected".

Find the probability of when d.f. = 22.

From a random sample of size 11, one has calculated the 95% confidence interval for $\mu$ and obtained the result (18.2, 28.4). If the population standard deviation is unknown, calculate a 98% confidence interval for $\mu$ .

Using the table for the t distributions, find the 97.5th percentile of the t distribution when d.f. = 11.

The coordinator of an advanced biology course took a random sample of the mid-term scores. Do these data substantiate the conjecture that the population mean score is larger than 65 points? Test at $\alpha$ =0.01.

Find the probability of -1.337 < T < 2.201 when d.f. = 16.

Find the probability of when d.f. = 12.

One year at the university pool, the winning times(min) for the winner of the women's 200 meter free style were What is the lower bound of a 98% confidence interval for the mean time?