Statistics question.

Question

Express the confidence interval -0.129 < p < 0.631 in the form of ± E.

Answer 1

Confidence interval is: p-E<p<p+E

To obtain the maximum error tolerance (E), find the difference of the 2 extremes:

 

(p+E) - (p-E) = 2E 

 

0.631-(-0.129) = 0.76

 

Thus, 2E = 0.76

 

E = 0.76/2 = 0.38

 

To obtain p, add 0.38 to -0.129 or subtract 0.38 from 0.631

 

Thus, (-0.129+0.38) = 0.631-0.38 = 0.251

 

Therefore: p ± E = p ± 0.38 or 0.251± 0.38