The weight, in grams, of pineapples is denoted by the random variable X which has a normal distribution with mean 500 and standard deviation 91.5. Pineapples weighing over 570 grams are classified as 'large'. Those weighing under 390 grams are classified as 'small' and the rest are classified as 'medium'.

Find the value of k such that P(k < X < 610) = 0.3

Can someone please help me with this?

I got the part until p(x<610)=1.202 ---->0.8853 from Ztable. now i dont understand why we have to minus 1 from this. it doesnt make any sense with my bell graph either . heeeelp!