Question 1131947


We know that {{{P(z < 0) = 0.5}}}, so {{{P(z<-a) = 0.50 - 0.1844 = 0.3156}}} 

Using a Standard Normal table ... 

{{{P(z<-a) = 0.3156{{{ has {{{a = 0.48 }}}

{{{P(-0.48<z<0) = 0.1844 }}}


or this way:

{{{P(-a<z<0) = 0.1844 }}}
{{{P( 0 < z < a) = 0.1844}}} (because of symmetry) 
{{{P( z < a) = 0.5+0.1844 = 0.6844 }}}

Look for {{{0.6844}}} under areas (in cumulative normal probability table) and read {{{z}}} backwards. 

{{{a=0.48}}} 
=>{{{-a=-0.48}}}