Answer: Choice Z (lower right corner)
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Explanation:
We start off with $5 in the piggy bank so x = 0 and y = 5 meaning (0,5) is one point on the curve. This narrows the choices down between X or Z (both on the right hand side). Choices W and Y have (0,10) on the graph so that's why we can rule them out.
After 1 year, the amount doubles. So we go from $5 to $10. At x = 1 year, the amount in the bank is y = 10 so the point (1,10) is on the curve. If you look closely, you'll notice that graph X does not have the point (1,10) on it, and instead it has something like (1,18). We can rule out graph X. Only graph Z has both (0,5) and (1,10) on the same curve. So this is why choice Z is the answer.
