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A psychologist wants to compare three methods for reducing hostility levels in university students. Eleven students...

A psychologist wants to compare three methods for reducing hostility levels in university students. Eleven students were judged to have "great hostility," based on a certain psychological test (HLT). These students were then randomly divided into three groups—five were treated by Method A, three were treated by Method B, and the other three students were treated by Method C. All treatments continued throughout a semester, at the end of which the HLT test was given again. The results are shown in the table.

Method Scores on the HLT Test
A 75 83 74 68 81
B 55 75 71
C 79 96 86

Let μA and μB, respectively, denote the mean scores for the populations of extremely hostile students who were treated by Methods A and B.

(a) Find a 95% confidence interval for μA. (Round your answers to two decimal places.)

(b)Find a 95% confidence interval for μB.  (Round your answers to two decimal places.)

(c)Find a 95% confidence interval for (μA − μB).  (Round your answers to two decimal places.)

Math   Statistics-And-Probability   
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