Data

For the tasks 1-8 (do not use R in tasks 3 and 5), consider the following data:

7.2, 1.2, 1.8, 2.8, 18, -1.9, -0.1, -1.5, 13.0, 3.2, -1.1, 7.0, 0.5, 3.9, 2.1, 4.1, 6.5

Question

(The calculations MUST be done manually, do not use R) Using techniques that we studied in this course, the upper and the lower cutoff points (rounded to three decimal places) for identifying outliers in the given data sample are: ____ and ____ (this is not a request to show any outliersjust the cutoff points that would determine what constitutes an outlier.) You may round to three decimal places

I have the answer from my assignment but I got it wrong. I just need to know the correct formula and understand how it is calculated precisely.