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7. From the normal curve of error, find the probability that a result is outside the limits of ±2σ from the mean. What is the probability that a result has a more negative deviation from the mean than -2σ?

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%…

A researcher would like to determine whether there is any relationship between students’ grades and where they choose to sit in the classroom. Specifically, the researcher suspects that the better students choose to sit in the front of the room. To test this hypothesis, the researcher asks her colleagues to help identify a sample of n = 100 students who all sit in the front row in at least one class. At the end of the semester, the grades are obtained for these students and the average grade point average is M = 3.25. For the same semester, the average grade point average for the entire college is μ = 2.95 with σ = 1.10. Use a two-tailed test with α = .01 to determine whether students who sit in the front of the classroom have significantly different grade point averages than other students.NOTICE that you are asked to use α = .01! A) sig., p<.01 B) N.S. ("not significant"), p>.01 C) sig., p>.01 D) N.S., p<.01

A chemist analyzes a sample of iron ore furnished by the National Institute of Standards and Technology, NIST. He obtains the following results: = 10.52%, s = 0.05, n = 10. The NIST's value for this sample is 10.60% Fe. Is the chemist's result (mean) significantly different at the 95% confidence level?

You determine the acetic acid (HOAc) content of vinegar by titrating with a sodium hydroxide standard solution to a phenolphthalein (an indicator) end point. An approximately 5-mL sample of vinegar is weighed on an analytical balance in a weighing boat and this is found to be 5.0268 g. The standard deviation in making a single weighing is 0.2 mg. The sodium hydroxide must be accurately standardised (this means its concentration must be accurately determined) by titrating known mass of high-purity potassium hydrogen phthalate, and three such titrations give molar concentrations of 0.1167, 0.1163 and 0.1164 mol L-1. A volume of 36.78 mL of sodium hydroxide is used to titrate each sample. The standard deviation of the burette used is 0.02 mL. Calculate the percentage of acetic acid in the vinegar and its standard deviation.

In a certain population, body weights are normally distributed with a mean of 152 pounds and a standard deviation of 26 pounds. How many people must be surveyed if we want to estimate the percentage who weigh more than 180 pounds? Assume that we want 96% confidence that the error is no more than 4 percentage points.

You begin preparation of the calibration curve to measure absorbance vs concentration of FeSCN²+. To do so, you add 1.58 mL of 0.200 M Fe(NO3)3 to a cuvette and then directly add 316 µL of 0.001 M KSCN. What is the resulting concentration of FeSCN2+, assuming complete conversion of SCN´¯ to FeSCN²+´ Enter your answer in units of mM to four digits after the decimal.

Estimate the absolute standard deviation (or uncertainty) for the results of the following calculations. Round each result so that it contains only  significant digits. The numbers in parentheses are absolute standard deviations. Show  your solution and express the final answer and its  corresponding uncertainty. a)  y= 2.998(±0.002)   - 3.98 (±0.15) + 9.035 (±0.002) = 8.0531 b)  y= 39.2(±0.3) x 3.054 (±0.022) x 10^ -2 = 1.197   c)   y= [198(±6)   - 89 (±3)] / 1335 (±2) + 64 (±7)]  = 7.791 x 10^-2

There samples of the same metal are weighed and their masses are found to be 42.02 g.4.63 g, and 44.16g. The corresponding volumes are 455 ml., 5.11 ml., and 4.84 m., respectively. Determine the density, d, of the metal and calculate the standard deviation of the density. d= The densities of several metals are given in the table. Metal (g/cm) aluminum 2.70 iron 7.87 cobalt 8.90 copper 8.96 gold 19.3 glemt Which of the metals could the sample be? gold cobalt D aluminoun copper g/cm³

After creating her standard curve for absorption versus the concentration (M) of FD&C Red 40 and processing her data, Sally found that her drinking strength Kool-Aid sample had an FD&C Red 40 concentration of 1.086 x 10–5 M. If 0.133 grams of Kool-Aid powder was used to prepare an 8-fl oz cup of her assigned flavor, what is the percent by mass of FD&C Red 40 in her Kool-aid powder?

What are replicates in Analytical Chemistry? O The component of a sample that repeats over different assays. Similar assays done to different samples A sample that contains exactly the same amount of analytes than the original sample similar samples that are analyzed at the same time and in the same way

After creating her standard curve for absorption versus the concentration (M) of FD&C Red 40 and processing her data, Sally found that her drinking strength Kool-Aid sample had a concentration of 4.692 x 10–5 M. If 0.132 grams of Kool-Aid powder was used to prepare an 8-fl oz cup of her assigned flavor, what is the percent by mass of FD&C Red 40 in her Kool-aid powder? Report your answer as a percentage with two places after the decimal. Do not include the percentage sign in your answer. Pay attention to units. You are trying to find the mass percentage of red dye, so you need to know each variable in the equation in Appendix B. Note that the percent by mass equation should be multiplied by 100. There may be some useful conversion factors in the experimental procedure.

Estimate the absolute deviation(or uncertainty) for the results of the following calculations. Round each result so that it contains only significant digits. The numbers in parentheses are absolute standard deviations. Finally, write the answer and its uncertainty.a.) Y= 6.75 (± 0.03) + 0.843(±0.001) - 5.021 (±0.001) = 2.572b.) Y= 19.97(± 0.04) + 0.0030(±0.0001) + 4.29(±0.08) = 24.263c.) Y= 143(± 6) - 64(±3) = 5.9578 x10-21249 (±1) +77 (±8)

If the mean value of certain set of eight measurements was 45.74, and standard deviation S=0.35. What is the confidence interval at 95% confidence level for the mean?

Suppose that in a random selection of 100 colored candies, 25% of them are blue. The candy company claims that thepercentage of blue candies is equal to 24%. Use a 0.05 significance level to test that claim.Identify the null and alternative hypotheses for this test. Choose the correct answer below.

3. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is a. 500 mg​​ b. 250 mg c. 60 mg 4. The method described above is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative error resulting from a 0.4-mg loss is not to exceed a. -0.1% b. -0.8%

Calculate the number of atoms in 264. µg of cadmium. Be sure your answer has the correct number of significant figures. Note: Reference the SI prefixes and Fundamental constants table for additional information. Cd atoms 0 x10 X