The determination of copper in a sca water sample gave a mean value of 77.81 ug/L and a standard deviation, s of 1.74 ug/L. How many samples must be analysed to obtain a relative standard deviation of 1.7% in the results at the 95% confidence level?

The determination of copper in a sca water sample gave a mean value of 77.81 ug/L and a standard deviation, s of 1.74 ug/L. How many samples must be analysed to obtain a relative standard deviation of 1.7% in the results at the 95% confidence level?

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

See similar textbooks

Similar questions

What is the relative average deviation in the following percent KHP values in ppt? (Enter your answer as a number without units.) 46.89 % 47.51 % 47.92 %
I am supposed to calculate Average absolute deviation (%). I am not sure if 7.16 is the final answer, or do i need to multiply by 100 because they are asking for percent?
3. How would you solve this ppm Ttest problem?
Calculate the mean and sample standard deviation for the following data: 90.0, 90.0, 85.0, 83.0, 80.0, 78.0, 77.0, 75.0, 70.0. Group of answer choices 79.8 ±± 5.83 79.8 ±± 6.23 80.9 ±± 6.75 80.9 ±± 6.37
Dr. Caras was characterizing a cytochrome (an iron containing protein) from a new strain of bacteria. He obtained eight measurements of the percent iron in the protein: 0.4908%, 0.4902%, 0.4899%, 0.4899%, 0.5012%, 0.4891%, 0.4903%, and 0.4892%. Calculate the mean (x) and standard deviation (s) for these results. x = S= Use the Grubbs test to determine if one of these values is an outlier. What is the value of Gcalculated? Gcalculated = % %
A chemical industry discharges a waste contaminated with trichloroethylene (TCE) to the city sewer system. By law, the concentration of TCE must be 1 mg/L or less. To enforce this law, the Department of Environmental Conservation (DEC) conducts random testing. The chief environmental engineer for the chemical company knows that the mean TCE concentration in the waste is 0.064 mg/L, and the standard deviation is 0.022 mg/L. The TCE concentration can be assumed to be a normal random variable. What is the probability that the company will fail a random test by the DEC? [In other words, the probability that a random sample will have TCE > 0.1 mg/L.] Show your work and draw a labeled sketch to show what area of the normal distribution curve you used to solve the problem. What is the probability that the company will fail two consecutive random tests? The tests can be assumed to be independent of each other. Show your work. Determine the concentration of TCE that is exceeded only 10%…
Trial Mass (g) 1 48.8839 2 49.0099 3 49.1121 4 48.9342 5 49.0338 6 48.7798 Calculate mean and standard deviation in the correct number of sigfigs
5
Determine the Average Mass and the Standard Deviation for the following data: Mass of pennies in grams = 1.5021, 1.4736, 1.4966, 1.5164, 1.5420, 1.4699 g. Average Mass grams +/- Standard Deviation grams
A student determines the concentration of an unknown sample using two different methods. Each method has three different trials; the average, standard deviation, and percent error produced by each method is listed below. Method 1 Average: 10.56 M NaOH Standard deviation: 1.35 M NaOH Percent error: 1.25% Method 2 Average: 10.92 M NaOH Standard deviation: 1.02 M NaOH Percent error: 3.45% Which method was more accurate? How can you tell?
Use a spreadsheet to calculate the mean and standard deviation of the data set. 54.99, 54.40, 54.60, 54.63, 54.36 The figure shows a suggested setup for your spreadsheet, where you enter the data in the highlighted cells and enter formulas in cells C4:D8 and B9:B11 to carry out the appropriate calculations. mean: standard deviation:
Student B determined the density of water to be 1.04 ± 0.05 g/mL. Consider Students A results. Which student was more accurate? Which student was more precise? (Student A got the following densities of water; 1.09 g/mL, 1.14 g/mL, and 1.15 g/mL with an average of 1.127 g/mL and a standard deviation of 0.026 g/mL)