Question 956843
I'm assuming you mean sigma (standard deviation) and not alpha. 
Find the z scores.
{{{z=(x-mu)/sigma}}}
{{{z[1]=(49-50)/5}}}
{{{z[1]=-0.2}}}
{{{z[2]=(53-50)/5}}}
{{{z[2]=0.6}}}
Find the probabilities corresponding the respective z scores.
{{{P[1]=0.42074}}}
{{{P[2]=0.72547}}}
So then,
{{{P=P[2]-P[1]}}}
{{{P=0.72547-0.42074}}}
{{{P=0.305}}}