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# Hypothesis Testing & Confidence Interval

2. In August 2003, 56% of employed adults in the United States reported that basic mathematical skills were critical or very important to their job. The supervisor of the job placement office at a 4-year college thinks this percentage has increased due to increased use of technology in the workplace. He takes a random sample of 480 employed adults and finds that 297 of them feel that basic mathematical skills are critical of very important to their job.

Has the percentage of employed adults who feel basic mathematical skills are critical or very important to their job increased? Use a significance level of .05. You must state the hypotheses, determine the test statistic and either the P-value(s) or critical value(s). Finally, you must clearly state your conclusion. Round all answers to two decimal places.

3. At what age do infants speak their first word of English? A simple random sample produced the following data on 20 children (ages are given in months):
15 26 10 9 15 20 18 11 8 20
7 9 10 11 11 10 12 17 11 10

Determine a 95% confidence interval for the age that infants speak their first work of English and provide a correct interpretation of your answer.

#### Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis and confidence interval. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.

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