Question 1105831
Assume a normal distribution.
Find the z score.
{{{z=(x-mu)/sigma}}}
{{{z=(90-60)/15}}}
{{{z=30/15}}}
{{{z=2}}}
Find the probability for {{{z=2}}} this will give you the probability for scores less than or equal to 90.
Subtract from 1 to find the complement or scores above 90.
{{{P(z=2)=0.97725}}}
So then,
{{{P=1-0.97725}}}