Answer:
The interquartile range is between 83.25 hours and 96.75 hours
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
Find the interquartile range for this distribution.
That is, the middle 50%, from the 25th to the 75th percentile.
25th percentile:
X when Z has a pvalue of 0.25. So X when Z = -0.675
75th percentile:
X when Z has a pvalue of 0.75. So X when Z = 0.675
The interquartile range is between 83.25 hours and 96.75 hours