Question

if the mean is subtracted from every number in a data set, and the differences are used to form a new data set, the data set must have a mean

Answer 1

Equal to original mean
Equal to zero
Smaller than original mean
Larger than original mean
CAnnot be determined

Answer 2

1 2 3 4 5 6 7 mean = 28/7 = 4

now subtracting 4 from all the numbers..
-3 -2 -1 0 1 2 3 4

so the new mean = ????