[tex]\mathbb P(X>3)=\mathbb P\left(\dfrac{X-2}{0.5}>\dfrac{3-2}{0.5}\right)=\mathbb P(Z>2)[/tex]
About 95% of a normal distribution lies within two standard deviations of the mean, so 5% lies without, and since the distribution is symmetric, 2.5% lies to either side. This means
[tex]\mathbb P(X>3)=\mathbb P(Z>2)\approx0.025[/tex]
