In: Statistics and Probability
A large consumer electronics retailer is planning to expand its e-commerce operations. To this end, the management is considering establishing a strategic partnership with courier company XYZ for the delivery of customers’ orders.
Estimate the extend of the difference in delivery times between ABC and XYZ at 95% confidence level.
Company ABC | Company XYZ |
18,42280727 | 18,11722091 |
23,25971383 | 18,03236506 |
24,47267508 | 11,70181582 |
16,43125944 | 28,6349246 |
24,28843419 | 20,01970193 |
28,94755272 | 21,43805892 |
23,99634997 | 25,77991841 |
21,24041049 | 17,61727736 |
13,03788468 | 23,17141939 |
22,48407401 | 19,44828346 |
11,75437848 | 16,47678806 |
25,32910531 | 27,07743766 |
28,29293481 | 22,60188244 |
18,07510972 | 21,75405717 |
18,52644874 | 17,69497663 |
27,387692 | 17,85126192 |
31,33021511 | 26,10624511 |
17,54311671 | 21,061494 |
19,60308128 | 20,38612598 |
24,13955445 | 23,3838603 |
22,91021548 | 27,90996637 |
24,93664016 | 15,98477416 |
17,39909368 | 15,16035132 |
23,66404789 | 21,78663413 |
26,33621608 | 25,21042693 |
34,52750735 | 25,72431418 |
28,47319212 | 22,36474307 |
20,53729378 | 21,05484901 |
21,29081923 | 20,54825477 |
14,71201432 | 16,49442088 |
24,47566959 | 15,64039399 |
14,28379238 | 18,38440203 |
12,40888724 | 23,25464953 |
18,93436393 | 18,26911221 |
29,47781996 | 18,64149345 |
22,68654117 | 25,70740895 |
22,51631105 | 20,85214458 |
24,03909167 | 23,93770199 |
31,76300726 | |
17,96011776 | |
28,38274287 | |
17,65424787 | |
27,28002602 | |
22,83645773 | |
23,3062072 | |
15,58564764 | |
25,03221213 | |
20,24033921 | |
26,41886186 | |
18,33414518 |
Write the relevant formulas in each case and show your calculations. Use appropriate tools from the Data Analysis Toolpak to verify your conclusions
Degree of freedom, DF= n1+n2-2 =
86
t-critical value = t α/2 =
1.9879 (excel formula =t.inv(α/2,df)
pooled std dev , Sp= √([(n1 - 1)s1² + (n2 -
1)s2²]/(n1+n2-2)) = 650439982.9385
std error , SE = Sp*√(1/n1+1/n2) =
139981861.7642
margin of error, E = t*SE = 1.9879
* 139981861.7642 =
278274731.2541
difference of means = x̅1-x̅2 =
2137753853.0800 -
1914772029.500 = 222981823.5800
confidence interval is
Interval Lower Limit= (x̅1-x̅2) - E =
222981823.5800 - 278274731.2541
= -55292907.6741
Interval Upper Limit= (x̅1-x̅2) + E =
222981823.5800 + 278274731.2541
= 501256554.8341
Please revert in case of any doubt.
Please upvote. Thanks in advance