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CBSE Class 12-science Answered

two balls are drawn from an urn containing 2 white 3 red and 4 black balls one by one without replacement. What is the probability that at least one ball is red?
Asked by Pragyashree Jain | 17 Mar, 2015, 04:54: PM
answered-by-expert Expert Answer
L e t space A space b e space t h e space e v e n t space o f space g e t t i n g space a space n o n minus r e d space b a l l space i n space t h e space f i r s t space d r a w space a n d l e t space B space b e space t h e space e v e n t space o f space g e t t i n g space a space n o n minus r e d space b a l l space i n space t h e space s e c o n d space d r a w. P open parentheses A close parentheses equals P r o b a b i l i t y space o f space g e t t i n g space a space n o n minus r e d space b a l l space i n space t h e space f i r s t space d r a w. rightwards double arrow P open parentheses A close parentheses equals 6 over 9 equals 2 over 3... left parenthesis 1 right parenthesis P open parentheses B close parentheses equals P r o b a b i l i t y space o f space g e t t i n g space a space n o n minus r e d space b a l l space i n space t h e space s e c o n d space d r a w. W h e n space a space n o n minus r e d space b a l l space i s space d r a w n space i n space t h e space f i r s t space d r a w comma space t h e r e space a r e space 5 space n o n minus r e d space b a l l s space a n d space 3 space r e d space b a l l s. T h e r e f o r e comma space f r o m space 5 space n o n minus r e d space b a l l s comma space o n e space b a l l space c a n space b e space s e l e c t e d space i n space C presuperscript 5 subscript 1 space w a y s. T h u s comma space P open parentheses B divided by A close parentheses equals 5 over 8.... left parenthesis 2 right parenthesis R e q u i r e d space p r o b a b i l i t y equals P r o b a b i l i t y space t h a t space a t l e a s t space o n e space b a l l space i s space r e d space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 1 minus P r o b a b i l i t y space o f space g e t t i n g space n o n minus r e d space b a l l space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 1 minus P open parentheses A space a n d space B close parentheses space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 1 minus P open parentheses A intersection B close parentheses space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 1 minus P open parentheses A close parentheses cross times P open parentheses B divided by A close parentheses space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 1 minus 2 over 3 cross times 5 over 8 space space space space space space space left square bracket f r o m space e q u a t i o n s space left parenthesis 1 right parenthesis space a n d space left parenthesis 2 right parenthesis right square bracket space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 7 over 12
Answered by Vimala Ramamurthy | 19 Mar, 2015, 09:06: AM

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CBSE 12-science - Maths
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Asked by armaanjain840 | 20 Dec, 2023, 05:59: PM
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CBSE 12-science - Maths
A bag contains 5 white balls and 9 red balls. Three balls are drawn from the bag. What is the probability that at least one ball is white?: Looks like answer posted as 55/182 is wrong. Request to recheck it once again.
Asked by sachinkumarmishra1 | 31 Jan, 2020, 05:17: PM
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CBSE 12-science - Maths
A bag contains 5 white balls and 9 red balls. Three balls are drawn from the bag. What is the probability that at least one ball is white?
Asked by sachinkumarmishra1 | 29 Jan, 2020, 02:59: PM
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CBSE 12-science - Maths
A bag contains 5 white balls and 9 red balls. Three balls are drawn, without replacement, from the bag. What is the probability that at least one ball is white?
Asked by sachinkumarmishra1 | 27 Jan, 2020, 12:27: PM
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CBSE 12-science - Maths
A bag contains 7 white , 5 Black and 4 red balls. 4 balls are drawn without replacement. Find the probability that atleast 3 balls are black.
Asked by sachinkumarmishra1 | 24 Jan, 2020, 11:10: AM
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CBSE 12-science - Maths
From a bag containing 8 white and 5 Black balls. Four balls are drawn one by one without replacement . Find the probability that exactly two of them are white.
Asked by sachinkumarmishra1 | 23 Jan, 2020, 12:00: PM
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CBSE 12-science - Maths
a bag contains 4 red ,6 green, 3 white balls ,three balls are drawn one after one the other without replacement,find the probability that the balls are red,green and green  My doubt is --How can we solve this question by combination ? The explanation given is    begin mathsize 16px style probability space of space taking space 1 st space ball space red space ball equals 4 over 13 probability space of space taking space 2 nd space ball space green space ball equals 6 over 12 space left parenthesis no space replacement right parenthesis probability space of space taking space 3 rd space ball space green space ball equals 5 over 11 space left parenthesis no space replacement right parenthesis so space in space total 4 over 13 cross times 6 over 12 cross times 5 over 11 end style  
Asked by sachinkumarmishra1 | 22 Jan, 2020, 05:50: PM
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CBSE 12-science - Maths
Neelam has offered physics , chemistry and mathematic sin class XII. She estimates that her probabilities of receiving a grade A  in these course are 0.2 , 0.3 and 0.9  respectively . Fins the probability that neelam receives : exactly 2A grades
Asked by haroonrashidgkp | 05 Nov, 2018, 02:11: PM
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CBSE 12-science - Maths
What are independent events? 
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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CBSE 12-science - Maths
If A and B are independent events, such that P(A) = , P(B) = , then find .       
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
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