I have a function f(x) where f(x)=3/8*(7-x)^2 when 5<=x<=7 and 0 otherwise.
I calculated the E(x)=5.5
and Std dev=.378
Now, I have a question asking this-
Find an exact interval within which 80% of the pH measurements must lie with half of the other 20% of the pH measurements lying below the lower limit and the other half lying above the upper limit.
I know this is chebychev's thm. but I have no idea how to apply it in this case