$\"\"$

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There are $\"\"$ red, $\"\"$ yellow, $\"\"$ blue, and $\"\"$ green balls.

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Find the probability $\"\"$ .

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The total number of balls are $\"\"$ .

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The number of red balls are $\"\"$ .

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The probability of red ball is $\"\"$ .

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$\"\"$ .

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The number of blue balls are $\"\"$ .

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The probability of red ball is $\"\"$ .

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$\"\"$ .

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The probability $\"\"$ : \ \

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$\"\"$ .

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$\"\"$ (Substitute $\"\"$ and $\"\"$ )

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$\"\"$ (Multiply)

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The probability is $\"\"$ or about $\"\"$ . $\"\"$

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The probability is $\"\"$ or about $\"\"$ .