The short answer is yes. One of the postulates of quantum mechanics is
"The state of any physical system is specified, at each time t, by a state vector [itex]|\psi(t) \rangle[/tex] in a Hilbert space, [itex]|\psi(t) \rangle[/tex] contains all the needed information about the system. Any superposition of state vectors is also a state vector."<br />
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In fact, even further, that is exactly how finding the probability of a state works for discrete spectra. For nondegenerate discrete eigenvalues the probability of obtaining one of the eigenvalues [itex]a_n[/itex] of an operator [itex]\hat{A}[/itex] is given by<br />
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[tex]P_n(a_n)=\frac{|\langle \psi_n | \psi \rangle|^2}{\langle \psi | \psi \rangle}[/tex]<br />
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where [itex]\psi_n[/itex] is the eigenstate of [itex]\hat{A}[/itex] with eigenvalue a_n.[/itex][/itex]