In my hypothetical example - I selected the numbers to be 2 & 2. Average (a) = 2 and SD (b) = 0. Now adding a 2 to it. New average (c) = 2 and new SD (d) = 0. I understand that the answer can be D or E here depending on the numbers you choose. Is my understand correct?
Yeah, I guess the question could use a fix.
which is just a 2, because sets can’t have repeats. But the flaw you caught still holds there, and hence this has been fixed.
agreed, fine catch. If it is stated that it is a set then the question is correct so what has been fixed?
Because b is still 0 for a set with one element, so the question was fixed by adding the condition b \neq 0.