For a density function

f(x) = 3 (x+4) / 14 for x=0 to x=1
Find P (2/5 < x < 2/3)

Please walk me through this problem.
Thanks

I'm sorry, is that function P(x) or f(x)?

Its function f(x)

It's asking to find the Probability P (2/5 < x < 2/3)

Sorry then, I'm unfamiliar with the problem :(. I was thinking it could be something else other than probability. I will go research this a bit and hopefully be able to provide and answer. Otherwise you will have to wait for a reply from someone who has a larger knowledge based around statistics

This is a probability density function. You integrate.

\frac{3}{14}\int_{\frac{2}{5}}^{\frac{2}{3}}(x+4)d x

Note that P(a\leq X\leq b)=F(b)-F(a)