Answer:[tex](y(x))^{2}[/tex]
Explanation:
The probability of fi in a range is given by the integral, whose limits are the range limits, of the square of the wave function y(x).
Example:
let's say range [a,b] with wave function y(x), then
[tex]Prob(a\leq x\leq b)=\int\limits^b_a {y(x)^{2} } \, dx[/tex]