A bag contains 6 white, 5 black and 4 red balls. Find the probability of getting either a white or a black ball in a single draw.

Answer

To solve the problem of finding the probability of drawing either a white or a black ball from a bag containing 6 white, 5 black, and 4 red balls, we can follow these steps:

### Step 1: Determine the total number of balls in the bag.
- The bag contains:
- 6 white balls
- 5 black balls
- 4 red balls

Total number of balls = Number of white balls + Number of black balls + Number of red balls
\[ \text{Total} = 6 + 5 + 4 = 15 \]

### Step 2: Determine the number of favorable outcomes.
- The favorable outcomes for drawing either a white or a black ball:
- Number of white balls = 6
- Number of black balls = 5

Total favorable outcomes = Number of white balls + Number of black balls
\[ \text{Favorable outcomes} = 6 + 5 = 11 \]

### Step 3: Calculate the probability of drawing either a white or a black ball.
- The probability \( P \) of an event is given by the formula:
\[ P(\text{Event}) = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} \]

Substituting the values we found:
\[ P(\text{White or Black}) = \frac{11}{15} \]

### Conclusion:
The probability of drawing either a white or a black ball in a single draw is:
\[ \frac{11}{15} \]

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