Question

Chapter 9 Lab Activity: Using Excel for Analysis of Two Means Following are weights in pounds for independent random samples of 25 newborn baby boys and baby girls in Denver in a recent year. Boxplots indicate that the samples come from populations that are approximately normal. Boys Girls 66 5.9 6.4 7.6 64 8.1 79 8.3 7.3 64 84 8.5 6.9 63 74 78 75 6.9 78 8.6 7.7 74 7.7 8.1 64 7 70 82 74 6.0 67 8.2 75 57 6.6 64 8.5 72 6.9 82 6.5 6.7 72 63 5.9 8.1 8.2 67 62 7.7 Can you conclude that the mean weights differ between boys and girls? Use the a0.05 level of significance. Use Excel to perform the hypothesis test. Upload your Excel file to Bh. State the null and alternate hypotheses that would be appropriate for this hypothesis test. Use proper notation and formatting. a. b. Give the value of the test statistic. Round to three decimal places ifneeded You may use either the p-value method or the critical value method to make a decision about whether to reject the null hypothesis. Please indicate which method you are using and include all relevant information that led to your decision. Clearly state your decision: Reject Ho or Do not reject Ho c. d. Choose an appropriate conclusion based on your decision in part c. i. The mean weights differ between newbom baby boys and girls ii. There is not enough evidence to conclude that the mean weights differ between newborn baby boys and girls.

Answer 1

Okay we would be using at t test for two independent samples in order to answer this question:

a.

The following null and alternative hypotheses need to be tested:

This corresponds to a two-tailed test, for which a t-test for two population means, with two independent samples, with unknown population standard deviations will be used.

b.

t Stat

1.268

c.

Using the P-value approach: The p-value is p = 0.210851435542421, and since p = 0.210851435542421≥0.05, it is concluded that the null hypothesis is not rejected.

d.

ii. There is not enough evidence to conclude that the mean weights differ between newborn baby boys and girls

The test run in excel is :

Girls t-Test: Two-Sample Assuming Equal Variances 1 Boys 2 6.6 7.1 Girls Boys 6.4 7.372 7.084 0.617933333 0.6714 25 4 8.2 Mean Variance Observations Pooled Variance Hypothesized Mean Difference df t Stat P(T<-t one-tail t Critical one-tail P(T< t) two-tail t Critical two-tail 6.4 25 6.7 8.2 8.3 7.3 6.4 8.4 8.5 6.9 6.3 10 5.7 6.6 6.4 8.5 7.2 6.9 8.2 6.5 6.7 7.2 6.3 1.268177042 0.105425718 1.677224197 0.210851436 2.010634722 12 13 14 15 16 17 7.5 6.9 19 20 21 8.6 7.7 23 24 8.2 6.7 6.2 7.7 7.7 6.4 26

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