A psychologist has prepared an "Optimism Test" that is administered yearly to graduating college seniors. The test measures how each graduating class feels about its future -the higher the score, the more optimistic the class.The psychologist wants to compare last year's class to this year's class to see if there is any difference.

Last year's class had a mean score of=15.A sample of9 seniorsfrom this year's class was selected and tested. They had a mean score ofM=10with aSS=94. Is this year's class significantly different? (usealpha =0.05)

1.Is this one-tailed or two-tailed?

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2.What is the critical value?

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3.What is the sample variance (SD²)?

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4.What is the standard error (SD_M)?

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5.Calculate the t-statistic

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6.What is your conclusion?

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1. What would your conclusion be if the significance level had been set at alpha = .01?

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