Answer:
33 inches per year
Step-by-step explanation:
In half a year, the sunflower grew 37 -20 1/2 = 16 1/2 inches. Your proportion is ...
(16 1/2 inches)/(1/2 year) = g/(1 year) . . . . . . . where g is the yearly growth
Multiplying by 1 year and simplifying, you can find g to be
g = (33/2 inches)/(1/2) = 33 inches
That is, the growth rate is 33 inches per year.
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Comment on the solution technique
I personally find a proportion to be unnecessary. When you want to find the rate of x per y, divide the amount of x you are given by the amount of y you are given.
Here, you are given a growth of 16 1/2 inches in 1/2 year, so you simply perform the division (16 1/2 inches)/(1/2 year) = 33 inches/year.