7 The times spent by people visiting a certain dentist are independent and normally distributed with a mean of 8.2 minutes. \(79 \%\) of people who visit this dentist have visits lasting less than 10 minutes.
- Find the standard deviation of the times spent by people visiting this dentist.
- Find the probability that the time spent visiting this dentist by a randomly chosen person deviates from the mean by more than 1 minute.
- Find the probability that, of 6 randomly chosen people, more than 2 have visits lasting longer than 10 minutes.
- Find the probability that, of 35 randomly chosen people, fewer than 16 have visits lasting less than 8.2 minutes.
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