Question 825303: A laboratory claims that the mean sodium level, μ , of a healthy adult is 143 mEq per liter of blood. To test this claim, a random sample of 80 adult patients is evaluated. The mean sodium level for the sample is 138 mEq per liter of blood. It is known that the population standard deviation of adult sodium levels is 15 mEq. Can we conclude, at the 0.05 level of significance, that the population mean adult sodium level differs from that claimed by the laboratory?
Perform a two-tailed test
1. The null hypothesis?
2. The alternative hypothesis?
3. The type test statistic
4. The value of the test statistic
5. The p value
6. Can we conclude that the population mean adult sodium levels differs from that claimed by the labratory.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A laboratory claims that the mean sodium level, μ , of a healthy adult is 143 mEq per liter of blood. To test this claim, a random sample of 80 adult patients is evaluated. The mean sodium level for the sample is 138 mEq per liter of blood. It is known that the population standard deviation of adult sodium levels is 15 mEq. Can we conclude, at the 0.05 level of significance, that the population mean adult sodium level differs from that claimed by the laboratory?
Perform a two-tailed test
1. The null hypothesis?:: Ho: u = 143 (claim)
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2. The alternative hypothesis?:: Ha: u # 143
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3. The type test statistic
4. The value of the test statistic:: t(138) = (138-143)/[15/sqrt(80)] = -2.98
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5. The p value = 2*P(t<-2.98 when df = 79) = 0.0038
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6. Can we conclude that the population mean adult sodium levels differs from that claimed by the labratory.
Since the p-value is less than 5%, reject the claim.
Yes, the sodium levels differ from that claimed by the laboratory.
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Cheers,
Stan H.
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