A random sample of size 20 taken from a normally distributed population revealed a sample mean of 77.5 and a sample variance of 48.4. The upper limit of a 95% confidence interval for the population mean would equal: a. 79.8786 b. 80.7560 c. 80.7451 d. 80.1897

Solve for D

Suppose 80 independent measurements are made for the speed of sound with an air temperature of 10 Celsius. The mean of the samples was 338.5 meters per second and the standard deviation was 2.2. Which of the statement below are True? a. Approximately 95% of the sample measurements need to be between 338.5 ± 1.96 * 2.2 for the mean of the sample to be normally distributed. b. Based on this sample, the 95% confidence interval for the true speed of sound at 10C is 338.5±1.96* 2.2/√80 c. The probability that the true speed of sound at 10C is between 338.5±1.96 * 2.2/√80 is 95%. d. The probability that the true speed of sound at 10C is between 338.5±1.65 * sqrt(2.2/80 is over 90%. e. Approximately 90% of the sample measurements were between 338.5±1.65 * 2.2/√80 f. The sample size of 80 is too small to judge the accuracy of the measurements.

Suppose that the waiting times for patients at a local hospital are normally distributed with known population standard deviation of 30 minutes. A random sample of 75 patients in the local hospital had a mean time of 90 minutes. Assume a 95% confidence interval for the population mean p. The formula used to calculate the standard error is O a. 0/n2 O b. o? /n O c. o/n O d. o/n

If the t-statistic for a single sample t-test is 1.58, what can you conclude? a. The test is significant at an alpha level of .05. b. The sample size of the test was at least 30. c. The sample mean was larger than the population mean. d. The population standard deviation was smaller than the difference between the sample mean and the population mean.

A given distribution has a population mean, μ, of 143 and a population standard deviation, σ, of 6.  What z-score would be associated with the value x = 112?

Using the simple random sample of weights of women from a data​ set, we obtain these sample​ statistics: n=445 and x =151.09 lb. Research from other sources suggests that the population of weights of women has a standard deviation given by sigmaσequals=30.94 lb. a. Find the best point estimate of the mean weight of all women. b. Find a 95​% confidence interval estimate of the mean weight of all women.