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Garcia\'s Garage desires to create some colorful charts and graphs to illustrate

ID: 389927 • Letter: G

Question

Garcia's Garage desires to create some colorful charts and graphs to illustrate how reliably its mechanics "get under the hood and fix the problem." The historic average for the proportion of customers that return for the same repair within the 30-day warranty period is

The answer is not A or C

the repair procss in contral? The UCLequals .170 and the LCL equals 0.050. iEnteryour.ncocnses rounded to mrcedeama, coco A. Since the sample proportion is close to one of the control imits the results are inconclusive. Thasamp praportion iswithin the contrel Imibs, so the repair procss snt in controll C C. The berofekn forrvice is bekw g bumge propertion is wit-in the cont ol liits, oepair procees is atil in oontrol D. The sample proportion is cutside the control limits, so the reir procesis in control. OE. The sampkc properian s outalde the control lmits, so the repair process is nat in control

Explanation / Answer

No of returns = 5 out of 110 customers

= 5/110*100 = 0.045

This is outside the control limits (not between 0.05 and 0.17), hence answer is E. The sample proportion is outside the control limits, so the repair process is not in control.