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Question
A box contains a certain number of balls. On each of 60% balls, letter A is marked. On each of 30% balls, letter B is marked and on each of remaining balls, letter C is marked. A ball is drawn from the box at random. Find the probability that the ball drawn is:
- marked C
- A or B
- neither B nor C
Solution
A box contains,
60% balls, letter A is marked.
30% balls, letter B is marked.
10% balls, letter C is marked.
i. Total number of all possible outcomes = 100
Number of favourable outcomes = 10
∴ Required Probability = `"Number of favourable outcomes"/"Total number of all possible outcomes"`
= `10/100`
= `1/10`
ii. The probability that the ball drawn is marked A = `"Number of favourable outcomes"/"Total number of all possible outcomes"`
= `60/100`
= `6/10` ...(1)
The probability that the ball drawn is marked B = `"Number of favourable outcomes"/"Total number of all possible outcomes"`
= `30/100`
= `3/10` ...(2)
iii. The probability that the ball drawn is neither B nor C
= 1 – [P(B) + P(C)]
= `1 - [3/10 + 1/10]`
= `1 - 4/10`
= `6/10`
= `3/5`
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