$\"\"$

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

Find the probability $\"\"$ .

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

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

$\"\"$ .

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

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

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