Answer:
[tex]\text{Probability}=\frac{w}{r+w}[/tex]
Step-by-step explanation:
Given : Suppose an urn has r red and w white marbles.
To find : Determine the probability that the marble is white ?
Solution :
Number of red marbles = r
Number of white marbles = w
Total number of marbles in an urn = r+w
Favorable outcome is getting the marble is white = w
So, Probability that the marble is white is given by
[tex]\text{Probability}=\frac{\text{Favorable outcome}}{\text{Total outcome}}[/tex]
[tex]\text{Probability}=\frac{w}{r+w}[/tex]