Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 12-science Answered

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
answered-by-expert Expert Answer
A bag contains 7 white , 5 Black and 4 red balls. 4 balls are drawn without replacement. To find the probability that atleast 3 balls are black.
 
T o t a l space n o. space o f space b a l l s space equals space 7 plus 5 plus 4 equals 16 P left parenthesis a t space l e a s t space 3 space b a l l s space a r e space b l a c k right parenthesis space equals space P left parenthesis e x a c t l y space 3 space b a l l s space a r e space b l a c k right parenthesis thin space plus space P left parenthesis A l l space 4 space b a l l s space a r e space b l a c k right parenthesis A s space t h e r e space a r e space 11 space n o n minus b l a c k space b a l l s space a n d space t h e s e space b a l l s space c a n space b e space a r r a n g e d space i n space 4 space w a y s space a m o n g space t h e m s e l v e s space P left parenthesis e x a c t l y space 3 space b a l l s space a r e space b l a c k right parenthesis space equals space fraction numerator C presubscript 1 presuperscript 5 over denominator C presubscript 1 presuperscript 16 end fraction cross times fraction numerator C presubscript 1 presuperscript 4 over denominator C presubscript 1 presuperscript 15 end fraction cross times fraction numerator C presubscript 1 presuperscript 3 over denominator C presubscript 1 presuperscript 14 end fraction cross times fraction numerator C presubscript 1 presuperscript 11 over denominator C presubscript 1 presuperscript 13 end fraction cross times 4 space space P left parenthesis A l l space 4 space b a l l s space a r e space b l a c k right parenthesis space equals space fraction numerator C presubscript 1 presuperscript 5 over denominator C presubscript 1 presuperscript 16 end fraction cross times fraction numerator C presubscript 1 presuperscript 4 over denominator C presubscript 1 presuperscript 15 end fraction cross times fraction numerator C presubscript 1 presuperscript 3 over denominator C presubscript 1 presuperscript 14 end fraction cross times fraction numerator C presubscript 1 presuperscript 2 over denominator C presubscript 1 presuperscript 13 end fraction therefore space P left parenthesis a t space l e a s t space 3 space b a l l s space a r e space b l a c k right parenthesis space equals space open parentheses 5 over 16 cross times 4 over 15 cross times 3 over 14 cross times 11 over 13 cross times 4 close parentheses plus open parentheses 5 over 16 cross times 4 over 15 cross times 3 over 14 cross times 2 over 13 close parentheses space space space space space equals space 5 over 16 cross times 4 over 15 cross times 3 over 14 cross times 1 over 13 open parentheses 11 cross times 4 plus 2 close parentheses equals 5 over 16 cross times 4 over 15 cross times 3 over 14 cross times 1 over 13 open parentheses 46 close parentheses equals 23 over 364
Answered by Renu Varma | 27 Jan, 2020, 12:14: PM

Concept Videos

Multiple Choice Questions Practice Test Subjective Questions Webinar Subjective Questions Pre Board Assessment
Answered Unanswered My Questions My Answers
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Maths
What are independent events? 
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 12-science - Maths
If A and B are independent events, such that = 0.8, P(B) = 0.6, then find the probability of occurrence of A.              
Asked by Topperlearning User | 04 Jun, 2014, 01:23: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt

Be a Top Scorer in the Exam with Test Series and Test Generator!

Enrol Now
×