When constructing a two-sided confidence interval for the mean of a normally distributed population with an 86% confidence level, what critical probability should be used to find the critical value?

An 86% two-sided confidence interval leaves 1 − 0.86 = 0.14 of the probability outside the interval. Split equally between the two tails, that is 0.07 in each tail, so the cumulative probability used to find the positive critical value is 1 − 0.07 = 0.93. The correct choice is 0.93.

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