<PRE><B>Question 163743</B>
1987, 34.7 million households owned a dog, and 27.7 million households owned a cat. Since 1987, dog ownership has decreased by about 0.025 million households per year, and cat ownership has increased by about 0.375 million households per year. If the trend continues, after how many years will the number of households that own dogs and cats be equal?
:
Let t = number of years for this to happen
:
Dog numbers = Cat numbers
34.7 - .025t = 27.7 + .375t
:
34.7 - 27.7 = .375t + .025t
:
7 = .4t
t = {{{7/.4}}}
t = 17.5 years
:
:
Check solution by finding the number of each in 17.5 yrs
34.7 - .025(17.5) =
34.7 - .4375 = 34.2625 million dogs
and
27.7 + .375(17.5) =
27.7 + 6.5625 = 34.2625 million cats

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