If an amount y depends on time t exponentially in such a way that the initial amount at t=0 is a and the decay factor is (1-r), then:
[tex]y=a(1-r)^t[/tex]As we can see, the base that is elevated to the time-dependent exponent is the decay factor. In the given expression:
[tex]y=500(0.75)^3[/tex]The factor that has the form of a decay factor is (0.75).
Therefore, the correct choice is: 0.75.
