SOLUTION: A woman is 61(1/12) inches tall and her son is 59(1/9) inches tall. How much taller is the woman?

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Question 782884: A woman is 61(1/12) inches tall and her son is 59(1/9) inches tall. How much taller is the woman?
Found 2 solutions by edjones, KMST:
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
61 1/12 - 59 1/9
=61 3/36 - 59 4/36 (36 is the LCD least common denominator)
=2199/36 - 2128/36 multiply the denominator times the integer + the numerator of each.
=71/36
=1 35/36 inches
.
Ed

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
The difference in their heights is
61%261%2F12-59%261%2F9
The result is 1%2635%2F36 inches of difference in their heights (almost 2 inches).
The mother is 1%2635%2F36 inches taller (almost 2 inches taller).
That makes sense because the approximation, calculated dropping the timy 1%2F12 and 1%2F9 fractions is
61 inches - 59 inches = 2 inches.

When we have to add or subtract fractions, we need a common denominator.
In this case, I would choose, 36, because it the smallest common multiple of 12 and 9:
12%2A3=36} and 9%2A4=36

THE HARD WAY:

That result can be simplified;
71%2F36=%2836%2B35%29%2F36=36%2F36%2B35%2F36=1%2B35%2F36=1%2635%2F36

MY WAY:


Sadly, teachers will probably favor the "HARD WAY".
It requires more complicated calculations, and mistakes are more likely, but students can memorize and (at least temporarily) remember a recipe to calculate the result. Understanding why such calculation are done that way; how and why calculations could be done differently, and/or how to estimate the result could be valuable bonuses.