Question 975205
Find the standard error.
{{{SE=sigma/sqrt(n)}}}
{{{SE=20/sqrt(20)}}}
{{{SE=sqrt(20)}}}
So then the margin of error equals,
{{{ME=z[c]*SE}}}
{{{ME=z[c]*sqrt(20)}}}
But you know the ME is equal to,
{{{ME=125-105=20}}}
{{{20=z[c]*sqrt(20)}}}
{{{z[c]=sqrt(20)}}}
Find the probability corresponding to a two tailed area between {{{-sqrt(20)}}} and {{{sqrt(20)}}}.
{{{P(-sqrt(20))=3.87x10^(-6)}}}
So then the area of interest is the area when you subtract twice this value from 1.
{{{P=0.99999}}}
Almost 100%.