Mean =12
Standard devation= 3.2863
variance???
A is the answer because it doesn’t have a repeating x value
If the number is n then
square of 2 times a number
square of 2n
(2n)²
that was your mistake, because (2n)²=4n², not 2n²
the result is 81
(2n)²=81
square root both sides
remember positive and negative roots
2n=+/-9
divide by 2
n=+/-4.5
n=4.5 or -4.5
