Pick some values for p, and play around at this website. As given, since you have no value for p, you cannot find a.
http://davidmlane.com/hyperstat/z_table.html
The Random Variable X is normally distributed with mean 560 and standard deviation 20.
Find P(X<530) which I calculated as 0.0668.
However... Next question asks
It is known that p(|X-560|<a)
Find the value of a
1 answer