Question 313892
Express the confidence interval in the form of P  ± E.  
 
 -0.128 < p <  1.212 
<pre><b>
First find the mean value (average) P of -0.128 and 1.212

{{{(-0.128+1.212)/2=1.084/2=0.542}}}

Then the difference between the mean value P and the lower value

{{{0.542-(-0.128)=0.542+0.128=0.67}}}

is the same as the difference between the upper value and the 
mean value

{{{1.212-0.542=0.67}}}

and this value is the "Error", E.

Thus in the form P ± E, the answer is

0.542 ± 0.67

Edwin</pre>