Statistics as level cie question help please

I think it's because the "new x" is 72

This thread is two years old....

Yes he did but you just seem as if you’re unhappy with his answer...

Every value in the data set has 50 subtracted from them, so you need to subtract 50 from your new piece of data if you are to incorporate it into the rest.
As for why we choose 50, you’d need to ask the actual person who came up with this question because it could’ve been any other number and there’s no actual need for it!