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![[Post New]](/templates/default/images/icon_minipost_new.gif) 12 Mar 2008 19:55:45 IST
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I'm unable to solve Probability probs please help me to do so, here is the NCERT TBQ Exercise 13.2 Q-1
An urn contains 5 red and 5 black balls. A ball is drawn at random, its color is noted and is returned to the urn. Moreover, 2 additional balls of the color drawn are put in the urn and then a ball is drawn at random. What's the probability that the second ball is red
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The deepest secret is that life is not a process of discovery, but a process of creation. You are not discovering yourself, but creating yourself anew. Seek therefore, not to find out who you are; seek to determine who you want to be."
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12 Mar 2008 20:02:18 IST
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To solve probability question you need to first understand the basic concepts of permutation and combination.
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12 Mar 2008 20:03:48 IST
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ok help me now
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The deepest secret is that life is not a process of discovery, but a process of creation. You are not discovering yourself, but creating yourself anew. Seek therefore, not to find out who you are; seek to determine who you want to be."
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12 Mar 2008 20:04:47 IST
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2 cases: black picked first...and red picked first
for black first:
1st:5/10 prob to pick black
now 7 black and 5 balls r there
so
5/10*5/12
similarly for red first:
5/10*7/12
so total probability
=1/2(5+7/12)
=1/2
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12 Mar 2008 20:08:12 IST
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why u've multiplied 5/10*5/12 Multiplication is done when events take place at the same time
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1. If the first ball selected is red. Probability = 5/10 Now 2 more red balls are added. Thus, No. of Red balls = 7 No. of Black balls = 5 Probability of selecting red ball = No. of red balls / Total balls = 7/(7+5) = 7/12 Total probability of this case = 5/10 * 7/12 2. If the first ball selected is black. Probability = 5/10 Now, 2 more black balls are added. Thus, No. of Red balls = 5 No. of Black balls = 7 Probability of selecting red ball = No. of red balls/ Total balls = 5/12 Total Probability of this case = 5/10 * (5/12) Total probability = 5/10 * 7/12 + 5/10 * 5/12 = 1/2
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12 Mar 2008 20:12:27 IST
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@anpm_dev...
i have multiplied because 5/10 is for first lift...and 5/12 is for SECOND lift
we multiply to find the pprobablity of these wo occuriing in the same event
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12 Mar 2008 20:15:23 IST
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o thanks i've rated u
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The deepest secret is that life is not a process of discovery, but a process of creation. You are not discovering yourself, but creating yourself anew. Seek therefore, not to find out who you are; seek to determine who you want to be."
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12 Mar 2008 20:18:06 IST
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how do u come so fast to a problem give some tips . i've to shake my mind hard for understanding the probability probs
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The deepest secret is that life is not a process of discovery, but a process of creation. You are not discovering yourself, but creating yourself anew. Seek therefore, not to find out who you are; seek to determine who you want to be."
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