SOLUTION: A random sample of 100 recorded deaths in an urban city during the past year showed an average life span of 71.8 years, with a standard deviation of 8.9 years. Does this seem to in

Question 557413: A random sample of 100 recorded deaths in an urban city during the past year showed an average life span of 71.8 years, with a standard deviation of 8.9 years. Does this seem to indicate that the average life span today is greater than the 70 years? (Use a 0.05 level of significance.)
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A random sample of 100 recorded deaths in an urban city during the past year showed an average life span of 71.8 years, with a standard deviation of 8.9 years. Does this seem to indicate that the average life span today is greater than the 70 years? (Use a 0.05 level of significance.)
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Ho: u = 70
Ha: u > 70 (claim)
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z(71.8) = (71.8-70)/[8.9/sqrt(100)] = 2.0224
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p-value = 2*P(z > 2.0224) = 0.0431
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Since the p-value is less than 5%, reject Ho.
The test results support the claim.
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Cheers,
Stan H.
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