guys take a look at this question:

If A has 25 items with average of 100. B has 30 items of which 25 of it has same average as A. the remaining 5 is equal to 100.

thus

B = A, 100,100,100,100,100

will they have same SD or not?

my response is they will have different SD. pls any prove why am wrong here.

thanks