A random sample of 116 lightning flashes in a certain region resulted in a sample average radar echo duration of 0.86 sec and a sample standard deviation of 0.36 sec. Calculate a 99% (two-sided) confidence interval for the true average echo duration ?. (Round your answers to two decimal places.)
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Interpret the resulting interval. Choose one below.
We are 99% confident that this interval does not contain the true population mean.
We are 99% confident that the true population mean lies above this interval.
We are 99% confident that the true population mean lies below this interval.
We are 99% confident that this interval contains the true population mean.