Answer:
SD = 10.1
Explanation:
We have been given that Kori knows that the mean of the data is 120 and that 84% of the data values are less than 130.
We will use z-score formula to find standard deviation of our given data set.
, where,
= z-score,
= Random sample score,
= Mean,
= Standard deviation.
Let us find z-score corresponding to the area of population under curve less than 84%.
From normal distribution table we get that z-score corresponding to area less than 84% is 0.99.
Upon substituting our given values in z-score formula we will get,



Therefore, the standard deviation of our given data set is 10.1.