Moo.
The Answer to the Cow Math Mystery
Did you figure it out?
I told you those diabolical creators of math story problems were tricky. Did you notice the fractions don’t add up to 1? Math story problems tend t0 suck you right into the story and in this case it got you worrying about whether or not the sons did the right thing first.
The answer was at the beginning of the story where the father lays out who gets how many cows. When he was divvying them up he made an error with his fractions:
1/2 + 1/3 + 1/9 ≠ 1
the least common denominator (LCD) for 2, 3, and 9 is 18 so the father wasn’t giving away enough of his cows.
9/18 + 6/18 + 2/18 = 17/18
You can see he was short by 1/18th of a cow. The first son got more than he should have (9 instead of 8.5). The second son should have only received 5.67 (5-2/3) instead of 6. And the youngest son should have only got 1.89 cows instead of 2 cows.
By the farmers accounting there should have been 17/18 of a cow left over (.944), so hamburgers and steaks would have been the only way to honor the farmer’s wishes.
How to Solve Math Story Problems
So the next time you do math story problems remember this example and follow these rules:
- Carefully read the entire story problem
- Make sure you understand what the story problem is asking, define your answer
- List all the variables in the problem and identify the units of measure if necessary (miles per hour, feet per second, etc.)
- Identify which variables are relevant to your answer, eliminate the unnecessary variables
- Use the text of the story problem to write an equation
- Be neat and organized with your answer
- Solve the equation!
Remember these rules and with a little practice you’ll be a math story problem pro.
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