Probability 1 Question 7
7. If 12 identical balls are to be placed in 3 different boxes, then the probability that one of the boxes contains excatly 3 balls, is
(2015 Main)
(a) $\frac{55}{3} \frac{2}{3}$
(b) $55 \frac{2}{3}^{10}$
(c) $220 \frac{1}{3}{ }^{12}$
(d) $22 \frac{1}{3}^{11}$
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Answer:
Correct Answer: 7. (a)
Solution:
- We have mentioned that boxes are different and one particular box has 3 balls.
Then, number of ways $=\frac{{ }^{12} C _3 \times 2^{9}}{3^{12}}=\frac{55}{3} \quad \frac{2}{3}{ }^{11}$
