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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%…

Consider the following sets of replicate measurements: (1) Calculate the mean and standard deviation of Group A. (2) Determine the confidence interval at 95% confidence level. Assume the data here are the only knowledge you have and no previous measurements are available.

4. In addition to finding the right answer can you explain what is Determinate error (I think the correct answer is the 3rd option here but not sure if right)

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?

The gold content of an ore is being measured. The results of these analyses are:  Content (ppt) 20.065 19.999 21.054 20.533 20.088 20.112 What is the average value, standard deviation and confidence interval for this set of data?Show each step of the calculation. Using your results calculate the %accuracy and %precision (relative standard deviation) if the true value is 20.045%.

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

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)

A method for the detection of morphine is used to generate a calibration curve in which the assay response (y) is plotted versus morphine concentration (x, in mg/L). This gives a straight line with a slope (m) of 0.241 and a y-intercept (b) of 0.011, where y = mx + b.  The slope of this line has a standard deviation of ±0.007, and the standard deviation of the intercept is ±0.006.  If the sample from an athlete gives a response of 0.506 ± 0.013 in this method, what is the concentration of morphine in the sample and estimated precision of this concentration?

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.