Posted by Patrick on .
The mean sleep time of babies is 14hrs,a sample of 64 babies showed a mean of 13hrs 30min with a standard deviation of 3hrs at 1% level of significance. Test the assertion that the mean sleep of the babies is less than 14hrs a day.

statistics 
PsyDAG,
Z = (mean1  mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability of the Z score. Is it more or less than .01? 
statistics 
SigmaStat,
Learn Hypothesis Step By Step
goo. gl/o0BTXy 
statistics 
lioioi,
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