Answer:
Sample mean = 7.1
Margin of error = 0.465
Step-by-step explanation:
Formula for confidence interval is;
CI = x¯ ± zE
Where;
x¯ is sample mean
z is critical value at confidence level
E is margin of error.
z for 99% Cl is 2.58
We are told the CI is 5.9 to 8.3.
Thus;
5.9 = x¯ - 2.58E - - - - (1)
8.3 = x¯ + 2.58E - - - - (2)
Add both equations together to get;
14.2 = 2x¯
x¯ = 14.2/2
x¯ = 7.1
Put 7.1 for x¯ in eq 1 to get;
5.9 = 7.1 - 2.58E
7.1 - 5.9 = 2.58E
E = 1.2/2.58
E = 0.465
The answer is c 16. Square cm
Answer:
Step-by-step explanation:
(x²-6x)+(y²+8y)=-21
(x²-6x+9)+(y²+8y+16)=-21+9+16
(x-3)²+(y+4)²=4
center=(3,-4),radius=√4=2
