Use the given graph of the function $f$ to answer the following questions. Assume that the graph extends only as far as is shown, that is only on the interval $(0,8)$.

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1. Find the open interval(s) on which $f$ is concave upward.
Answer (in interval notation):

2. Find the open interval(s) on which $f$ is concave downward.
Answer (in interval notation):

3. Find the coordinates of the points of inflection. List your answers as points in the form $(a,b)$.
Answer (separate by commas):

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Note: You can click on the graph to enlarge the image.

Hint: