Question

Part (a)    Using the THE TABLE BELOW that is posted with the assignment, carry out a “t-test: Two-Sample Assuming Unequal Variances” in Excel (with α = 0.05) that tests whether there is a difference in mean maintenance costs between buses with Diesel engines and those with gasoline engines. using Excel file include the output as part of the answer Part (b)    Based on the t-test, what is your decision (“reject” or “do not reject”) regarding the null hypothesis that the two population means are equal to each other? Indicate on which part of the Excel output you base your decision. Part (c)    Explain what the decision in part (b), i.e., “rejecting H0” or “not rejecting H0” means in this context at a level that can be understood by a high school senior. USE THE FOLLOWING TABLE Buena School District Bus Data - Monthly Maintenance Cost (in Dollars) by Engine Type

Maintenance Cost for Buses with Diesel Engines	Maintenance Cost for Buses with gasoline Engines
503	514
380	466
432	359
329	427
503	474
505	382
546	474
561	558
357	497
329	459
489	355
455	436
503	514
380	406
432	474
478	382
471	422
444	474
493	558
452	360
461	460
496	423
469	477
433	453
561	444
357	457
329	461
525	455
374	462
389	470
450
561
581
427
366
382
370
400
527

Answer 1

Sol:

in excel install analysis tool pak then go to

Data>Data analysis>t test assuming unequal variance

You will get

Output:

t-Test: Two-Sample Assuming Unequal Variances
	Maintenance Cost for Buses with Diesel Engines	Maintenance Cost for Buses with gasoline Engines
Mean	448.7179487	451.7666667
Variance	5160.62888	2645.426437
Observations	39	30
Hypothesized Mean Difference	0
df	67
t Stat	-0.205309159
P(T<=t) one-tail	0.418976545
t Critical one-tail	1.667916114
P(T<=t) two-tail	0.837953091
t Critical two-tail	1.996008354

Part (b)   
Based on the t-test, what is your decision

(“reject” or “do not reject”) regarding the null hypothesis that the two population means are equal to each other?

Indicate on which part of the Excel output you base your decision.

t stat=-0.2053

p value=0.838

p>0.05

do not reject null hypothesis

Part (c)   

Explain what the decision in part (b), i.e., “rejecting H₀” or “not rejecting H₀”

means in this context at a level that can be understood by a high school senior

if p<alpha reject Ho.

if p>alpha ,fail to reject Ho.

here alpha=0.05

p value for two tail  0.838