Answer:
x would equal -11 or 13
Step-by-step Explanation:
x(x - 2) - 143 = 0
x^2 - 2x - 143 = 0
-2x + x^2 = 143
-143 + (-2x) + x^2 = 0
(x - 13)(x + 11)
x - 13 = 0
Add 13 to both sides
x = 13
x + 11 = 0
Subtract 11 from both sides
x = -11
The confidence interval is from 0.2191 to 0.2649, given by

.
The z-score we need is found by first subtracting the confidence level from 1:
1 - 0.95 = 0.05
Divide that by 2:
0.05/2 = 0.025
Subtract that from 1:
1 - 0.025 = 0.975
Look this up in the middle of a z-table (http://www.z-table.com) and we see that the z-score is 1.96.
Now our confidence interval is given by
2/21 * 7/8
14/168
divide top and bottom by 14
1/12