The probability that the sampled element will be less than 45 is given by the normal distribution cdf at 45:

= Norm.cdf( x, mean, sd )

= Norm.cdf( 45, 57.7, 12.1 )

= 0.147

(This is because the cdf of the distribution gives you the total probability up to that point, i.e. the area under the distribution curve to the left of whatever x is)