Question

A bag contains 10 black balls, 5 red balls and 5 white balls and a ball is drawn randomly from it. What is the probability of getting either a red or a white ball?

• A. \(1/4 \)
• B. \(1/2 \)
• C. \(3/4 \)
• D. \(1 \)

Hint:

You can also solve this by finding the probability of the "opposite" event. Since the only other option is a black ball, $P(\text{Red or White}) = 1 - P(\text{Black})$.
$1 - (10/20) = 1/2$.

Answer 1

The Correct Option is B

Concept: The probability of an event is the ratio of favorable outcomes to the total number of outcomes. For mutually exclusive events (like drawing different colored balls), the probability of "Either A or B" is the sum of their individual probabilities.
Step 1: Find the total number of balls in the bag.
Total balls = 10 (Black) + 5 (Red) + 5 (White) = 20 balls.

Step 2: Find the number of favorable outcomes.
Favorable outcomes (Red or White) = 5 (Red) + 5 (White) = 10.

Step 3: Calculate the probability.
\[ P(\text{Red or White}) = \frac{\text{Favorable outcomes}}{\text{Total outcomes}} = \frac{10}{20} = \frac{1}{2}. \]