Question

Lisa Monnin is the budget director at Nexos Media, Inc. She wants to compare the daily expenses of diets of the sales staff with the expenses of the audit staff, for which she compiled the following information about the samples. Sales ($) 845 826 827 875 784 809 802 820 829 830 842 832 Audit ($) 841 890 821 771 850 859 825 829 If we assume that the standard population deviations are equal and at a significance level of 0.10, can Monnin conclude that the average daily expenses of sales personnel are greater than those of the audit staff? What is the value of p?

Answer 1

x1: Sales

x2: Audit

n1 = 12

= 826.75

s1 = 22.8399

n2 = 8

= 835.75

s2 = 34.4041

Claim: The average daily expenses of sales personnel are greater than those of the audit staff.

The null and alternative hypothesis is

Level of significance = 0.10

The population standard deviations are equal.

So we have to use here pooled standard deviation.

Test statistic is

Degrees of freedom = n1 + n2 - 2 = 12 + 8 - 2 = 18

Critical value = 1.330    ( Using t table)

P-value = P(T > - 0.71) = 0.7555

| t | < critical value we fail to reject the null hypothesis.

Conclusion: The average daily expenses of sales personnel are NOT greater than those of the audit staff.