Question

A box contains 20 identical balls of which 10 are blue and 10 are green. The balls are drawn at random from the box one at a time with replacement. The probability that a blue ball is drawn 4th time on the 7th draw is

• A. \( \frac{27}{32} \)
• B. \( \frac{5}{32} \)
• C. \( \frac{1}{32} \)
• D. \( \frac{1}{16} \)

Hint:

When calculating probabilities in multiple trials, use the multiplication rule for independent events.

Answer 1

The Correct Option is B

The probability of drawing a blue ball on the 4th draw is \( \frac{1}{2} \). The probability of the blue ball appearing on the 7th draw can be calculated as \( \frac{5}{32} \) by considering the total number of possible outcomes.
Step 2: Conclusion.
The correct answer is (B), \( \frac{5}{32} \).