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Question
A bag contains 5 white and 7 red balls. One ball is drawn at random. What is the probability that ball drawn is not black?
Solution
GIVEN: A bag contains 6 red, 8 black and 4 white balls and a ball is drawn at random
TO FIND: Probability that the ball drawn is not black
Total number of balls `6+8+4=18`
Total number of black balls is 8
We know that PROBABILITY =` "Number of favourable event" /"Total number of event "`
Probability of getting a black ball P(E) `8/18=4/9`..........(1)
We know that sum of probability of occurrence of an event and probability of non occurrence of an event is 1.
Hence
`P(E)+P(overlineE)=1`
`4/9+P(overlineE)=1`
`P(overlineE)=1-4/9`
`P(overlineE)=5/9`
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