We have 3⁴ = 81, so we can factorize this as a difference of squares twice:

Depending on the precise definition of "completely" in this context, you can go a bit further and factorize
as yet another difference of squares:

And if you're working over the field of complex numbers, you can go even further. For instance,

But I think you'd be fine stopping at the first result,

Answer:
Since the sample size is larger than 30, the cognitive psychologist can assume that the sampling distribution of M will be approximately normal.
Step-by-step explanation:
We use the central limit theorem to solve this question.
The Central Limit Theorem estabilishes that, for a random variable X, with mean
and standard deviation
, a sample size larger than 30 can be approximated to a normal distribution with mean
and standard deviation 
So
Since the sample size is larger than 30, the cognitive psychologist can assume that the sampling distribution of M will be approximately normal.
The angles must add to 180 degrees.
Since the angles are in the ratio 7:9:4, their measures are not 7, 9, and 4 since 7, 9, and 4 do not add to 180. If you multiply 7, 9, and 4 by the same number, the new numbers will be in the same ratio. Since we do not know what that number is, we can use x for it.
Multiply 7, 9, and 4 by x to get
7x, 9x, and 4x.
Now add them and set equal to 180.
Then solve for x.
7x + 9x + 4x = 180
20x = 180
x = 9
Now that we know x equals 9, substitute x with 9 and evaluate 7x, 9x, and 4x to find the actual angle measures.
7x = 7 * 9 = 63
9x = 9 * 9 = 81
4x = 4 * 9 = 36
The angles measure 63, 81, and 36 degrees.
Answer:
Hello! Your answer would be, A)
Step-by-step explanation:
Hope I helped! Ask me anything if you have more questions! Have a nice mourning! Hope you make an 100%! -Amelia♥