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Answer:
[tex]a_n=200\cdot \frac{1}{4}^{(n-1)}[/tex]
Step-by-step explanation:
Since the sequence begins with 200 and each next term in the sequence is a quarter of the previous one, an equation for this would be:
[tex]a_n=200\cdot \frac{1}{4}^{(n-1)}[/tex]
You can see that this works by testing out some scenarios. For instance, the third term in the sequence:
[tex]a_3=200\cdot \frac{1}{4}^{(3-1)}= 200\cdot \frac{1}{16}=12.5[/tex]
Hope this helps!