Hi there! Hopefully this helps!
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It <u>decreased by 30 cents</u> per week.
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The average <em>rate of change</em> is calculated as:
the <u>ratio of the sum of the change</u> in the three weeks <u>divided by</u> <u>the number of weeks. (</u>The <em>number of weeks</em> being <u>3</u>)
<em>Rate of change</em> = .
(-60 + -10 + -20 = -90). So, to <em>simplify</em> it:
= <u><em>-30</em></u>
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Incase you are confused:
Since the average <u>rate of change</u> is <em>negative</em>, this means that the <u>stock price</u> has <em>decreased</em>.