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pakinam
 one year ago
The durations of phone calls taken by the receptionist at an office are like draws made at random with replacement from a list that has an average of 8.5 minutes (that's 8 minutes and 30 seconds) and an SD of 3 minutes. Approximately what is the chance that the total duration of the next 100 calls is more than 15 hours?
pakinam
 one year ago
The durations of phone calls taken by the receptionist at an office are like draws made at random with replacement from a list that has an average of 8.5 minutes (that's 8 minutes and 30 seconds) and an SD of 3 minutes. Approximately what is the chance that the total duration of the next 100 calls is more than 15 hours?

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kropot72
 one year ago
Best ResponseYou've already chosen the best response.0\[X=\frac{15\times 60}{100}=9\ minutes\] \[z=\frac{X\mu}{\sigma}=\frac{98.5}{3}=0.1667\] Reference to a standard normal distribution table shows that the cumulative probability of calls averaging less than 9 minutes is 0.5662. Therefore the chance that the total duration of the next 100 calls is more than 15 hours is 1.0000  0.5662

kyusakazaki
 one year ago
Best ResponseYou've already chosen the best response.0@kropot72 that's incorrect , thnx
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