document.write( "Question 776317: is 40 years old. He asks you to test his thinking. You collect a sample of 50 customers and found that the average age is 38.7. Assuming that the population standard deviation is 12.5 years and using α = 0.05, test your manager's hypothesis. What is your conclusion?
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Algebra.Com's Answer #473528 by AnlytcPhil(1806)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "It's complete enough to know what you mean.\r\n" );
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document.write( "H0\r\n" );
document.write( "μ = 40\r\n" );
document.write( " H1\r\n" );
document.write( "μ < 40\r\n" );
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document.write( "If the mean really is 40 with the standard deviation of 12.5\r\n" );
document.write( " then we find the probability that 38.7 would be that low or\r\n" );
document.write( "lower, and if it's less than 5% of the time, it's too unlikely\r\n" );
document.write( "and we'll reject the null hypothesis, but if it's not we won't.\r\n" );
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document.write( "Calculate the z-score:\r\n" );
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document.write( "x - m   38.7 - 40\r\n" );
document.write( "————— = ————————— = -.7353910524\r\n" );
document.write( "  \"sigma%2Fsqrt%28n%29\"       \"12.5%2Fsqrt%2850%29\"\r\n" );
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document.write( "1. The first way you have to know the cut off points for the\r\n" );
document.write( "various alpha error values.\r\n" );
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document.write( "In the case of a left one-tail test with alpha = 0.05 you have to \r\n" );
document.write( "have the cut-off point of -1.64, for that's the value that has 0.05 \r\n" );
document.write( "of the area to the left of it.\r\n" );
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document.write( "2. The second way you find the p-value, which is the area to the\r\n" );
document.write( "left of the z-score -.735  which is 0.2312, which is higher than\r\n" );
document.write( "0.05. \r\n" );
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document.write( "When the p-value is high, the null must fly.\r\n" );
document.write( "When p-value is low, the null must go\r\n" );
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document.write( "Here the p-value is high, so the null must fly, so we fail to reject \r\n" );
document.write( "the null hypothesis.\r\n" );
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document.write( "Edwin

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