Question 375919
{{{z=(x-mu)/sigma}}}
{{{z=(225-170)/30}}}
{{{z=1.5}}}
.
.
.
{{{P(x<=225)=P(1.5)}}}
Find P(z).
Then

{{{P(x>225)+P(x<=225)=1}}}
{{{P(x>225)=1-P(x<=225)}}}
{{{P(x>255)=1-P(1.5)}}}