TAKE YZ = 34
A recent public relations fiasco has intensifieddemand for engine testing for a particular OEM of
agricultural machinery. Historically, these engines are estimatedto have a constant failure rate of 7
failures per 10000 + YZ (ten thousand + YZ) hours.
A local TV station is testing the engines under two differenttrials (25 hours and 100 hours)
What is the reliability of a single engine after 25 hoursAND 100 hours?
What is the probability of no failed engines, a single failedengine, and more than one failed
engine, if the engines are tested in batches of 5 engines? Use thePoisson method and fill in the table on
the next page, for both the 25 hour test and the 100 hour test.(show one sample calculation below)
0 failed 1 failed >1 failed TOTAL
100.00 % (25 hours)
100.00 % (100 hours)
Two separate third party labs are also testing the enginebut using some different criteria.
Number of engines tested Number Failed
Lab 1 220+YZ 43
Lab 2 127 25
Formulate the hypothesis comparing the two labs, using the Z testfor binomial trials (difference in
proportions). What significance did you find?
