Question

A list is obtained of birth weights from 30 consecutive, full-term, live-born deliveries from the maternity ward of a hospital in a low-SES area. The mean birthweight (???) is found to be 115 oz. with a sample standard deviation (s) of 24 oz. We know from nationwide surveys based on millions of deliveries that the mean birthweight in the United States is 120 oz. Use the onesample t test to test the hypothesis H0: ? = 120, H1: ? < 120 using a significance level of .05.

Answer 1

we have

we have to use the one sample t test in order to test the hypotheses

Using the formula for the test statistic, we can write

t =

setting the given values, we get

t =

now, using the online calculator at http://www.socscistatistics.com/pvalues/tdistribution.aspx with degree of freedom n-1 = 30-1 = 29

we get the required p value = 0.1316 > 0.05 significance level

so, it is clear that the calculated p value is not significant, thus we fail to reject the null hypothesis.

so, we can conclude that there is not enought evidence to support the alternate hypothesis.

we get