Question

A study of iron deficiency among infants compared samples of infants following different feeding regimens. One group contained breast-fed infants, while the infants in another group were fed a standard baby formula without any iron supplements. Here are summary results on blood hemoglobin levels at 12 months of age. Group n x s Breast-fed 22 13.1 1.7 Formula 20 12.5 1.8

(a) Is there significant evidence that the mean hemoglobin level is higher among breast-fed babies? State H0 and Ha.

H0: μbreast-fed = μformula; Ha: μbreast-fed > μformula

H0: μbreast-fed < μformula; Ha: μbreast-fed = μformula

H0: μbreast-fed > μformula; Ha: μbreast-fed = μformula

H0: μbreast-fed ≠ μformula; Ha: μbreast-fed < μformula

Carry out a t test. Give the P-value. (Use α = 0.01. Use μbreast-fed − μformula. Round your value for t to three decimal places, and round your P-value to four decimal places.)

t =

P-value =

What is your conclusion?

Reject the null hypothesis. There is not significant evidence that the mean hemoglobin level is higher among breast-fed babies.

Reject the null hypothesis. There is significant evidence that the mean hemoglobin level is higher among breast-fed babies.

Fail to reject the null hypothesis. There is significant evidence that the mean hemoglobin level is higher among breast-fed babies.

Fail to reject the null hypothesis. There is not significant evidence that the mean hemoglobin level is higher among breast-fed babies.

Answer 1

Given that,

For Breast-fed :

For Formula :

The null and alternative hypotheses are,

H0: μbreast-fed = μformula

Ha: μbreast-fed > μformula

Using TI-84 calculator we get,

Test statistic = t = 1.108

p-value = 0.1374

since, p-value is greater than α = 0.01

=> Fail to reject the null hypothesis. There is not significant evidence that the mean hemoglobin level is higher among breast-fed babies.