A random sample of 8 size AA batteries for toys yield a mean of 3.41 hours with standard deviation, 1.3 hours. (a) Find the critical value, t*, for a 99% Cl. t* = (b) Find the margin of error for a 99% CI.

Pulse rates of adult men are approximately normal with a mean of 70 and a standard deviation of 8. Which choice correctly describes how to find the proportion of men that have a pulse rate greater than 78? (a) Find the area to the right of z = -1 under a standard normal curve. (b) Find the area to the right of z=1 under a standard normal curve. (c) Find the area to the left of z = 1 under a standard normal curve. (d) Find the area between z=-1 and z=1 under a standard normal curve. (e) None of the above

an extensive study conducted in 1980 concluded that the mean mercury level in oysters from the white bear estuary was 0.020 parts per million (ppm) with a standard deviation σ = 0.022. In 2012, a sample of 48 oysters from the same estuary exhibited a mean mercury concentration of 0.004 ppm. can you conclude that the 2012 mercury concentration is lower than in 1980? use the α = 0.01 level of significance. A). yes. the mercury concentration appears to be lower in 2012 B). No. there is insufficient evidence to conclude that the mercury concentration has decreased from 1980 to 2012  C). there is not enough information to reach a conclusion

The finished inside diameter of a piston ring is normally distributed with a mean of 10 centimeters and a standard deviation of 0.03 centimeter. If in a couple of years, the mean and the standard deviation of the nished inside diameter of a piston ring change both to dierent values μ and σ, what proportion of rings will have inside diameters exceeding μ + 2.5σ?

I need letter d. Thank you!

A population of students earned test scores distributed normally with a mean of 65 and a standard deviation of 9. Find the percent of scores with a grade of F. Identify the following variables: μ: σ: x1: x2:z1 = , z2 = The percent of students that earned a grade of F, between 0 and 60, is = % Enter your answers as numbers accurate to 2

A random sample of 16 adult male wolves from the Canadian Northwest Territories gave an average weight x₁ = 97 lb with estimated sample standard deviation s₁ = 6.7 lb. Another sample of 26 adult male 14 wolves from Alaska gave an average weight x2 = 88 lb with estimated sample standard deviation $₂ = 7.5 lb. USE SALT (a) Let u represent the population mean weight of adult male wolves from the Northwest Territories, and let μ2 represent the population mean weight of adult male wolves from Alaska. Find a 75% confidence interval for μ1-2. (Round your answers to one decimal place.) lower limit upper limit (b) Examine the confidence interval and explain what it means in the context of this problem. Does the interval consist of numbers that are all positive? all negative? of different signs? At the 75% level of confidence, does it appear that the average weight of adult male wolves from the Northwest Territories is greater than that of the Alaska wolves? Because the interval contains only…