14. 3 points lllowskyintroStat1 7.HW.095. My Notes Ask Your Your company has a c

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14. 3 points lllowskyintroStat1 7.HW.095. My Notes Ask Your Your company has a contract to perform preventive maintenance on thousands of air-conditioners in a large city. Based on service records from previous years, the time that a technician spends servicing a unit averages one hour with a standard deviation of one hour. In the coming week, your company will service a simple random sample of 50 units in the city. You plan to budget an average of 1.1 hours per technician to complete the work. will this be enough time? (Suppose your company will assume this is enough time if there is a 90% chance the maintenance will be less than 1.1 hours. Round your probability to four decimal places.) The probabilty it wl take less than 1.1 hours is approximately Because this is Select 90%, more time ..-Select- needed. Submit Answer Save Progress Practice Anolher Version

Explanation / Answer

here from normal normal approximation P(Xbar<1.1)=P(Z<(1.1-1)/(1/sqrt(50))=P(Z<0.71)=0.7611

hence the probabiliy it will take less than 1.1 hours is approximately 0.7611 becuase this si less than than 90% more time is needed,

(please try probability =0.7602 if above comes wrong)

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