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About LinkBacksA bag contains 5 Black and 3 red balls.A ball is taken out of a bag and is not returned to it.If the process is treated 3 times then what is the probability of drawing a black ball in the next draw of a ball?
a) 0.7
b) 0.625
c) 0.1
d) None of these.
A bag contains 5 Black and 3 red balls.A ball is taken out of a bag and is not returned to it.If the process is treated 3 times then what is the probability of drawing a black ball in the next draw of a ball?
a) 0.7
b) 0.625
c) 0.1
d) None of these.
Thought process -
I think the three balls can be drawn in 4 ways
1) All the three balls are black = 5/8 .4/7 .3/6 then the probability of next black ball can be drawn is 2/5.
2) 2 black and 1 red = 5/8 . 4/7 . 3/6 then the probability of next black ball can be drawn is 3/5.
3) 1 black and 2 red = 5/8 . 3/7 . 2/6 then the probability of next black ball can be drawn is 4/5.
4) All red = 3/8 . 2/7 . 1/6 then the probability of next black ball can be drawn is 1.
Probability = (option1 + option 2 + option3 + option 4)/chosing one out of four
= (2/5 + 3/5 + 4/5 + 1)/4C1 = 14/20 = 0.7
Please let me know if the way I am thinking is right.
Anshu.
You have correctly identified the four possibilities.Originally Posted by Curious_eager
But what you have not done correctly is to calculate the probabilities of each option.
For example, #2 should be:.
If done correctly by adding we get.
It is curious to note that is exactly the probability of getting a black on the first draw.
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