Question

# The mean birth weight of male babies born to 121 mothers taking a vitamin supplement is...

The mean birth weight of male babies born to 121 mothers taking a vitamin supplement is

3.633.63

kilograms with a standard deviation of

0.630.63

kilogram. Use a 0.05 significance level to test the claim that the mean birth weight of all babies born to mothers taking the vitamin supplement is equal to 3.39​ kilograms, which is the mean for the population of all male babies.

State the null and alternative hypotheses. Find the z-score and the P value and make a conclusion.

Here' the answer to the question. Please let me know in case you've problem understanding the solution

Xbar = 3.63
Stdev = 0.63
n = 121
alpha = .05
Pop. Mean = 3.39

The null and alternate hypothesis is :
Ho: Mu = 3.39
Ha: Mu !=3.39

Lets calculate the Z test-statistic
= (Xbar-Mean)/(Stdev/sqrt(n))
= (3.63-3.39)/(.63/sqrt(121))
= +4.1905

Z score is 4.1905

p-value = P(|z|>4.1905) = 2.7837E-05
[we make use Z table to convert to a probability value or the Excel formula =NORMSDIST(z)]

This is less than .05

Conclusion: No, claim that the mean birth weight of all babies born to mothers taking the vitamin supplement is equal to 3.39​ kilograms is FALSE