Wilson Corporation - Case Study The certified letter was delivered about 4:00 PM

Question

Wilson Corporation - Case Study

The certified letter was delivered about 4:00 PM to Andrew Wilson, CEO and principal owner of the Wilson Corporation. It was from the State Department of Environmental Services and it sent shivers down Andrew’s spine. In bold-faced type at the top of the letter was the message:

“Notice of Water Quality Violation – Wilson Corporation”

The letter went on to outline the situation. The state had performed tests at the outflow location from Wilson’s main processing plant and found problems with nitrates and pH levels. A hearing on the matter was scheduled on Tuesday, June 27, 2017 to outline the issues and to assess damages to be paid by the Wilson Corporation. In the meantime, all effluent from the plant was to be immediately halted.

Accompanying the letter was a computer disk file containing data from 95 water samples selected at the Wilson plant over a 3-week period. The file is labeled Wilson Water.

Andrew reached for his phone to make two calls. The first was to Randy Glover, his production scheduler. He told Randy the problem and indicated that he was to immediately halt production and to schedule an employee meeting at 8:00 the next morning.

The second call went to his statistical group. Andrew explained to them the essence of the letter and the action he was taking with regard to production. He wanted them to halt all other work and immediately perform an analysis on the sample data supplied by the state. Andrew wanted a comprehensive descriptive and inferential (confidence intervals & hypothesis tests) analysis of the data by midnight Monday, June 26, 2017, so he could prepare for the hearing with the state. He would like to have a report that discusses the data.

Be sure to incorporate into your report statistical information you obtained using Microsoft Excel. Set up appropriate confidence interval estimates and summarize your findings in words. What should the company conclude about its current status on meeting the federal requirements? One of the requirements is that the average pH level does not exceed 7.4. For the nitrates, the maximum allowable level is 3.0 milligrams per milliliter. Test these hypotheses at the 0.05 level of significance. Discuss your results in a memo to the company’s CEO.

pH Nitrates 7.82 8.2 7.9 6.7 7.9 7.3 7.82 6.8 7.8 7.1 7.5 7.4 7.6 6.4 7.5 7.2 7.6 2.5 7.81 3 7.77 3.3 7.6 3.5 7.2 3.9 7.5 2.9 7.3 3.2 7.4 3.4 7.4 3.8 7.6 3.6 7.75 8.2 7.9 5.8 7.8 4.6 7.65 6.3 8 8.1 7.8 7.5 7.6 6.4 7.6 9 7.6 2.5 7.6 2.9 7.7 3.5 7.26 3.9 7.5 3.5 7.2 3 7.6 3.1 7.4 3.1 7.4 3.5 7.4 3.4 7.6 0.38 7.54 7.7 7.7 5.4 7.7 6.6 7.3 6.4 7.6 6.8 7.6 4.9 7.6 5.7 7.6 2.1 7.7 2.7 7.4 4 7.7 3.8 7.3 4.5 7.4 3 7.3 2.8 7.3 3 7.6 3.3 7.1 3 7.3 0.315 7.77 7 7.41 5.8 8.1 5.9 7.9 7.2 7.6 7.3 7.9 4.9 7.9 7 7.6 2.1 7.9 2.7 7.65 3.5 7.6 4 7.7 3.5 7.4 3.6 7.6 2.5 7.2 2.9 7.6 3.1 7.5 3.3 7.8 3 7.7 6.8 7.99 7.2 7.9 6.6 8.1 5.3 7.8 6.4 7.81 7.2 7.8 6.3 7.9 7.1 7.79 2.1 7.9 2.9 7.7 3.2 7.8 3.9 7.5 4 7.6 2.8 7.8 2.8 7.3 3.1 7.4 3.3 7.5 2.8 7.8 5.3 7.6 1.8 7.91 2.9 8.06 3.8

Explanation / Answer

Answer:

Set up appropriate confidence interval estimates and summarize your findings in words. What should the company conclude about its current status on meeting the federal requirements? One of the requirements is that the average pH level does not exceed 7.4. For the nitrates, the maximum allowable level is 3.0 milligrams per milliliter. Test these hypotheses at the 0.05 level of significance. Discuss your results in a memo to the company’s CEO.

pH level:

Confidence Interval Estimate for the Mean

Data

Sample Standard Deviation

0.2218

Sample Mean

7.6306

Sample Size

95

Confidence Level

95%

Intermediate Calculations

Standard Error of the Mean

0.022751302

Degrees of Freedom

94

t Value

1.9855

Interval Half Width

0.0452

Confidence Interval

Interval Lower Limit

7.5855

Interval Upper Limit

7.6758

The mean pH level is 7.63. 95% Confidence interval for pH level is ( 7.5855, 7.6758).

The 95% confidence level values above the 7.4 level. We conclude that average pH level exceed 7.4.

Confidence Interval Estimate for the Mean

Data

Sample Standard Deviation

1.9686

Sample Mean

4.5452

Sample Size

95

Confidence Level

95%

Intermediate Calculations

Standard Error of the Mean

0.201970818

Degrees of Freedom

94

t Value

1.9855

Interval Half Width

0.4010

Confidence Interval

Interval Lower Limit

4.1442

Interval Upper Limit

4.9462

The mean nitrates level is 4.54 milligrams per milliliter. 95% Confidence interval for pH level is ( 4.14, 4.95).

The 95% confidence level values above the 3.0 level. We conclude that average nitrates exceed 3.0 level.

The company concludes that the current status not met the federal requirements.

Confidence Interval Estimate for the Mean

Data

Sample Standard Deviation

0.2218

Sample Mean

7.6306

Sample Size

95

Confidence Level

95%

Intermediate Calculations

Standard Error of the Mean

0.022751302

Degrees of Freedom

94

t Value

1.9855

Interval Half Width

0.0452

Confidence Interval

Interval Lower Limit

7.5855

Interval Upper Limit

7.6758

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