Statistics
posted by Erik .
Lead (Pb) concentrations were measured in waterfowl eggshell samples from two locations. In n1 = 41 samples from a location downstream from a paper mill, the mean Pb concentration was 1 x = 0.13 ppm with a standard deviation of s1 = 0.04 ppm. In n2 = 31 samples from a location upstream from the paper mill, the PB concentration was 2 x = 0.09 ppm with a standard deviation of s2 = 0.05 ppm. Test the hypothesis of no difference in mean Pb eggshell concentrations versus the alternative that the locations downstream from the papermill have a higher mean Pb concentration. Use a 1% level of significance.

Z = (mean1  mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.
Respond to this Question
Similar Questions

Statistics
hi i need help calculating the standard error using the central limit theorem. *a population of scores contains exactly 5 scores : 2, 3, 6, 8, 11, there are 5x5=25 samples of the two scores (n=2)* i already calculated the standard … 
Statistics
If the standard deviation of a population is 56 and we want the standard error (the standard deviation of the sample mean) to be 14, then we need to take how many samples? 
Statistics
This is the first question..... For a population that has a standard deviation of 10, figure the standard deviation of the distribution of means for samples of size (b) 3. This is the second question....For each of the following samples … 
statistics
For each of the following samples that were given an experimental treatment, test whether these samples represent populations that are different from the general population: (a) a sample of 10 with a mean of 44, (b) a sample of 1 with … 
statistics
For each of the following samples that were given an experimental treatment, test whether these samples represent populations that are different from the general population (a) a sample of 10 with a mean of 44, (b) a sample of 1 with … 
statistics
For each of the following samples that were given an experimental treatment, test whether these samples represent populations that are different from the general population: (a) a sample of 10 with a mean of 44, (b) a sample of 1 with … 
statistics
Suppose that the height of male students at a large university is normally distributed with a mean of 69 inches and a standard deviation of 3.0 inches. If 16 samples consisting of 25 students each are obtained, what is the probability … 
Statistics
Through extensive research, Metlife Insurance claims that the mean footwell intrusions for Toyota Corrola and Toyota Rav4 are equal. Crash test at 40mph were performed at 7 randomly selected Toyota Corrola and 13 randomly Toyota Rav4s … 
Statistics
Through extensive research, Metlife Insurance claims that the mean footwell intrusions for Toyota Corrola and Toyota Rav4 are equal. Crash test at 40mph were performed at 7 randomly selected Toyota Corrola and 13 randomly Toyota Rav4s … 
Statistics
Lead (Pb) concentrations were measured in waterfowl eggshell samples from two locations. In n1 = 41 samples from a location downstream from a paper mill, the mean Pb concentration was 1 x = 0.13 ppm with a standard deviation of s1 …