ABSTRACT
The mean of the numbers 1, 2 and 4 can be calculated in R as https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429492259/53d5c801-629e-4918-87c2-f91e21eef379/content/page3_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
