Probability stats

Question

Suppose a geyser has a mean time between eruptions of

84 minutes84 minutes.

Let the interval of time between the eruptions be normally distributed with standard deviation

34 minutes34 minutes.

Complete parts ​(a) through ​(e) bel

Answer 1

Mean 84, standard deviation 34 minutes?

Some standard multiple choice questions might involve the 68, 95, 99 rule, such that 68% of the eruptions occur within one standard deviation of the mean. Here that would be 84 plus or minus 34 or within 50 minutes to 114 minutes. Also 95% of the time the eruptions would be within 2 standard deviations, or 84 plus or minus 68, or 84-68=16 minutes and 84+68=152 minutes. 99% of the time eruptions would be within 3 standard deviations, which gets below zero, so stick with just zero to 84 + or - 3 times 34, or zero to 84 plus or minus 102 = [0, 186] Nearly all the time eruptions will be within 186 minutes or 3 hours

Sometimes it's called the 68-95-99.7 rule, as it really is almost a full 100% of the data falling within 3 standard deviations.

Just a guess that a standardized test might refer to something above in an a through e type question set