Answer
$$y=600(1.05)^t$$
Work Step by Step
Note that $\frac{630}{600} = \frac{661.5}{630} = \frac{694.58}{661.5} = \frac{729.3}{694.58} = 1.05$
So, each next number is 1.05 times the previous number.
$$y(t+1) = 1.05y(t)$$
We are given that it is an exponential function so $$y(t)=Cb^t$$
By this, we get, $Cb^{t+1}= 0.6Cb^t$
Or $$b=1.05$$
Putting t = 0 gives, $y(0) = Cb^0 =600$
Or $$C = 600$$
Therefore, $$\boxed{y=600(1.05)^t}$$
