Author:
Christine Farr

In a metal fabrication process, metal rods are produced to a specified target length of 15 feet. Suppose that the lengths are normally distributed. A quality control specialist collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and a standard deviation of 0.65 feet. The standard error of the mean is A 0.65 ft.B 0.1625 ft.C 0.0098 ft.D 0.346 ft.E 1.625 ft.EU (European Union) countries report that 46% of their labor force is female. The United Nations wants to determine if the percentage of females in the U.S. labor force is the same. Based on a sample of 500 employment records, representatives from the United States Department of Labor find that the 95% confidence interval for the proportion of females in the U.S. labor force is 0.357 to 0.443. Which of the following is the correct interpretation? A We are 95% confident that between 35.7% and 44.3% of the persons in the U.S. labor force is femaleB The margin of error for the true percentage of females in the U.S. labor force is between 35.7% and 44.3%C The percentage of females in the U.S. labor force is between 35.7% and 44.3%D All samples of size 500 will yield a percentage of females in the U.S. labor force that falls within 35.7% and 44.3%E None of theseIn a metal fabrication process, metal rods are produced to a specified target length of 15 feet. Suppose that the lengths are normally distributed. A quality control specialist collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and a standard deviation of 0.65 feet. Which of the following statements is true? A The sampling distribution for the sample mean follows the t-distribution with 15 degrees of freedomB The mean of the sampling distribution for the sample mean is 14.8 feetC The standard error is 0.65 feetD The sampling distribution for the sample mean follows the t-distribution with 16 degrees of freedomE The sampling distribution for the sample mean is Normal with a mean of 14.8 feet and standard deviation of 0.65 feet

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