Question

Ms. Lisa Monnin is the budget director for Nexus Media Inc. She would like to compare the daily travel expenses for the sales staff and the audit staff. She collected the following sample information.

Sales ($)	127	137	140	159	136	138
Audit ($)	123	102	128	143	153	127	131

At the 0.050 significance level, can she conclude that the mean daily expenses are greater for the sales staff than the audit staff?

1. State the decision rule. (Round your answer to 3 decimal places.)

2. Compute the pooled estimate of the population variance. (Round your answer to 2 decimal places.)

3. Compute the test statistic. (Round your answer to 3 decimal places.)

4. State your decision about the null hypothesis.

• Do not reject H₀: μ_s ≤ μ_a

• Reject H₀: μ_s ≤ μ_a

5. Estimate the p-value.

• Between 0.10 And 0.15

• Between 0.001 And 0.005

• Between 0.005 And 0.01

• Between 0.01 And 0.025

Answer 1

a)

degree of freedom='(n1+n2-2)=		43
for 0.05 level ,right tail test &43 df, critical t=			1.681
Decision rule : reject Ho if test statistic t>1.681

b)

sample mean x =	139.500	129.571
standard deviation s=	10.559	16.040
sample size n=	6	7
Pooled Variance Sp2=((n1-1)s21+(n2-1)*s22)/(n1+n2-2)=			191.02

c)

Point estimate : x1-x2=		9.9286
std. error se =Sp*√(1/n1+1/n2)=		7.6893
test stat t =(x1-x2-Δo)/Se=		1.291

d) Do not reject H₀: μ_s ≤ μ_a

e)

p value : =

0.1116

from excel: tdist(1.291,11,1)

Between 0.10 And 0.15