Answer: 
Step-by-step explanation:
The confidence interval estimate for the population mean is given by :-
, where
is the sample mean and ME is the margin of error.
Given : Sample mean: 
The margin of error for a 98% confidence interval estimate for the population mean using the Student's t-distribution : 
Now, the confidence interval estimate for the population mean will be :-

Hence, the 98% confidence interval estimate for the population mean using the Student's t-distribution = 
Answer:
Solution set = {-12, 12}
Step-by-step explanation:
Start by dividing both sides of the given equation by negative one, to get rid of the negative signs on both sides:

Now we consider the two possible cases:
1) The expression inside the absolute value symbol is a positive number, then :

and replacing it in the equation, this becomes:

which is our first answer.
2) The expression inside the absolute value symbol is a negative number, then :

and replacing it in the equation, this becomes:

which is our second possible answer.
Then the set of solutions is: {-12, 12}
(A)
Step-by-step explanation:
All other choices will result in a negative number inside the radical sign.
Answer:
Center = (5, -2) and radius = √33
Step-by-step explanation:
The equation of a circle is given by the formula;
(x-a)² + (y-b)² = r² ; where (a,b) is the center of the circle and r is the radius of the circle.
In this case;
2x² - 20x + 2y² + 8y =40 ;
Dividing both sides of the equation by 2 we get;
x² - 10x + y² + 4y = 20
we can then use the completing the square on both x and y terms.
x² - 10x + y² + 4y = 20
x² + 2(-5)x + 25 + y² + 2(2) y + 4 = 20 +9 + 4
In standard form we get;
(x-5)² + (y+2)² = 33
Therefore;
Center = (5, -2) and radius = √33