YX=2, I assume you need to get the 'X' and 'Y' alone. Also just for future reference, you're trying to get variables alone and all the numbers on the other side. Lastly, whatever you do to one side you do to the other. Good luck!
Let X be a random variable representing the weight of a pack of cookies.
P(X < 250) = P(z < (250 - 255)/2.5) = P(z < -5/2.5) = P(z < -2) = 1 - P(z < 2) = 1 - 0.97725 = 0.02275 = 2.3%
Therefore, we conclude that about 2.3% of the packs weighed less than 250 grams.
1/0.125
I really hope this helps
