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 ($)	129	135	148	160	135	144
Audit ($)	122	103	127	136	129	120	142

At the 0.025 significance level, can she conclude that the mean daily expenses are greater for the sales staff than the audit staff?

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

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

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

3. State your decision about the null hypothesis.

• Reject H₀: μ_s ≤ μ_a

• Do not reject H₀: μ_s ≤ μ_a

5. Estimate the p-value.

• Between 0.01 And 0.025

• Between 0.001 And 0.005

• Between 0.005 And 0.01

• Between 0.025 And 0.05

Answer 1

degree of freedom='(n1+n2-2)=		11
for 0.025 level ,right tail test &11 df, critical t=			2.201	from excel: t.inv(0.975,11)

Decision rule : reject Ho if test statistic t>2.201

a )

	Sales	Audit
sample mean x =	141.83	125.57
standard deviation s=	11.23	12.55
sample size n=	6	7
Pooled Variance Sp2=((n1-1)s21+(n2-1)*s22)/(n1+n2-2)=			143.32

b)

Point estimate : x1-x2=		16.2619
std. error se =Sp*√(1/n1+1/n2)=		6.6605
test stat t =(x1-x2-Δo)/Se=		2.442

c)

Reject H₀: μ_s ≤ μ_a

e)

Between 0.01 And 0.025