A report in a research journal states that the average weight loss of people on a certain drug is 34 lbs with a margin of error of ±2 lbs with confidence level C = 95%. (a) According to this information, the mean weight loss of people on this drug, ?, could be as low as lbs. (b) If the study is repeated, how large should the sample size be so that the margin of error would be less than 1 lbs? (Assume σ= 7 lbs.)

A researcher studying the lifespan of a certain species of bacteria. A preliminary sample of 30 bacteria reveals a sample mean of ¯x=68x¯=68 hours with a standard deviation of s=7s=7 hours. He would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.75 hours at a 99% level of confidence.What sample size should you gather to achieve a 0.75 hour margin of error?He would need to sample  bacteria.

To compare the dry braking distances from 30 to 0 miles per hour for two makes of​ automobiles, a safety engineer conducts braking tests for 35 models of Make A and 35 models of Make B. The mean braking distance for Make A is 43 feet. Assume the population standard deviation is 4.6 feet. The mean braking distance for Make B is 46 feet. Assume the population standard deviation is 4.5 feet. At α=0.10​, can the engineer support the claim that the mean braking distances are different for the two makes of​ automobiles? Assume the samples are random and​ independent, and the populations are normally distributed.   The critical​ value(s) is/are   Find the standardized test statistic z for μ1−μ2.

Question 4 Previous Ne QUESTION 28 A manufacturer measures 19 randomly selected dowels and finds the standard deviation of the sample to be s 0.16. Find the 95% confidence interval for the population variance. A) (0.0146, 0.2370) B) (0.0146, 0.0560) C) (0.1210, 0.2370) D) (0.0210, 0.0560) A