The time t that technician requires to perform preventive maintenance on an air conditioning unit has an unknown probability distribution. however, its mean is known to be 2 hours, with standard deviation 1 hour. suppose the company maintains 70 of these units and that the conditions of the central limit theorem apply. what is the probability that a maintenance operation will take more than 2 hours and 15 minutes?

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Step-by-step explanation:

To calculate the probability that a maintenance operation will take more than 2 hours and 15 minutes. We can first calculate the probability that ALL maintenance operation on 70 of the units will take less than 2 hours and 15 minutes, then subtract it from 1.

So the probability of a maintenance operation that would take less than 2 hours and 15 minutes, or 135 minutes is:

So the probability that a maintenance operation will take more than 2 hours and 15 minutes is:

a. the residual plot for model 1 has a random pattern and is a good fit for the data.

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step-by-step explanation: