Answer: Decay; -7% increase
You could also say "7% decrease" but it looks like your teacher wants "increase" in there, so you have to make the value negative.
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Explanation:
The base of the exponential is 0.93
Compare this to 1+r and we see that 1+r = 0.93 solves to r = -0.07
The negative r value indicates exponential decay. Specifically we have 7% decay. The amount is decreasing by 7% each time x increases by 1 unit.
The phrasing "7% decrease" is the same as "-7% increase", though in my opinion, "7% decrease" sounds more natural and easier to conceptualize.
