Both methods assume a normal distribution of the data, but the z-tests are most useful when the standard deviation is known.
OR u can use , z-tests are used when we have large sample sizes (n > 30), whereas t-tests are most helpful with a smaller sample size (n < 30). Both methods assume a normal distribution of the data, but the z-tests are most useful when the standard deviation is known.
Answer:
-7
Step-by-step explanation:

Since angle A = Angle B, I believe you would write it out like this:
6x+12=3x+63
subtract 3x from both sides, then subtract 12 from both sides.
3x=51
divide 51 by 3 to find x.
x=17
Now to find the measure of angle A.
A = 6(17)+12
A = 102+12
A = 114, angle A is 114 degrees.
Answer:
x = 2 and y = -2
Step-by-step explanation:
We must first eliminate the y-variable:
2x + 3y = -2
3x - 6y = 18
4x + 6y = -4
3x - 6y = 18
_________
7x = 14
x = 2
Since we know x=2, we plug that back into one of the original equations to find y:
2x + 3y = -2
2(2) + 3y = -2
4 + 3y = -2
3y = -6
y = -2
Therefore, x = 2 and y = -2
A.
Solve both of the equations for t^2. Then set them equal to each other and solve.