SOLUTION: The old assembly line method for assembling a product had a mean of 40 minutes. With a new assembling line method, for a random sample of 16 unites of the product, the mean assembl

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Question 981084: The old assembly line method for assembling a product had a mean of 40 minutes. With a new assembling line method, for a random sample of 16 unites of the product, the mean assembling time per unit of product is 38 minutes with a sample std. deviation 4 minutes. Using a level of significance of 0.05, test whether the mean time to assemble with the new method is less than that for the old method. Use t as test statistic.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Ho=mu= or greater than 40
Ha=mu less than 40
alpha=0.05
Test statistic is t df=15 (x-40)/4/sqrt (16)
Critical value is T< -1.753 (one tail); reject if t df=15 is less
calculation is (-2)(4)/4=-2; I like to invert the denominator and put sqrt (n) in the numerator.
This is less than the critical value (or greater negative than the critical value)
Reject the null hypothesis.
Conclude that the new method is faster.