Question 1061655
a) z-score for 30 = (30 - 25) / 5.8 = 0.8621
z-score for 20 = (20 - 25) / 5.8 = -0.8621
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Note find probabilities from z-tables
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Probability ( 20 < X < 30 ) = 0.8051 - 0.1949 = 0.6102
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b) standard deviation of the sample = 5.8 / square root(25) = 1.16
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c) z-score for 30 = (30 - 25) / 1.16 = 4.31
z-score for 20 = (20 - 25) / 1.16 = -4.31
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Probability ( 20 < X < 30 ) = 0.9999 - 0.0003 = 0.9996
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