Answer: 0.0215 .
Step-by-step explanation:
Let X denotes the weekly wages at a certain factory .
It is normally distributed , such that
[tex]X\sim N(\mu=400,\ \sigma= 50)[/tex]
Then, the probability that a worker selected at random makes between
$250 and $300:
[tex]P(250<X<300)=P(\dfrac{250-400}{50}<\dfrac{x-\mu}{\sigma}<\dfrac{300-400}{50})\\\\=P(\dfrac{-150}{50}<z<\dfrac{-100}{50})\ \ [z=\dfrac{x-\mu}{\sigma}]\\\\=P(-3<z<-2)\\\\=P(z<-2)-P(z<-3)\\\\=1-P(z<2)-(1-P(z<3))\\\\=P(z<3)-P(z<2)\\\\=0.9987-0.9772\\\\=0.0215[/tex]
Hence,the required probability = 0.0215 .