document.write( "Question 1162936: We use the t distribution to construct a confidence interval for the population mean when the underlying population standard deviation is not known. Under the assumption that the population is normally distributed, find tα/2,df for the following scenarios. (You may find it useful to reference the t table. Round your answers to 3 decimal places.)\r
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\n" ); document.write( " tα/2,df
\n" ); document.write( "a. A 95% confidence level and a sample of 18 observations.
\n" ); document.write( "b. A 99% confidence level and a sample of 18 observations.
\n" ); document.write( "c. A 95% confidence level and a sample of 9 observations.
\n" ); document.write( "d. A 99% confidence level and a sample of 9 observations.
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the critical t-score will be as follows:
\n" ); document.write( "with 18 observations, the degrees of freedom = 17
\n" ); document.write( "with 9 observations, the degrees of freedom = 8
\n" ); document.write( "i used the following table:
\n" ); document.write( "https://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf\r
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\n" ); document.write( "\n" ); document.write( "at 95% confidence level, the two tail critical t-score will be 2.306 with 8 degrees of freedom and 2.110 with 17 degrees of freedom.\r
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\n" ); document.write( "\n" ); document.write( "at 99% confidence level, the two tail critical t-score will be 3.355 with 8 degrees of freedom and 2.898 with 17 degrees of freedom.\r
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\n" ); document.write( "\n" ); document.write( "note that the two tail critical t-score at .05 is the same as the one tail critical t-score at .025 and the two tail critical t-score at .01 is the same as the one tail critical t-score at .005.
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