A-box-contains-2-blue-1-red-balls-We-randomly-draw-one-ball-then-put-it-back-and-add-two-balls-of-the-same-color-of-that-ball-in-the-box-We-randomly-draw-again-one-ball-if-it-was-red-then-what

Question Number 180775 by Acem last updated on 17/Nov/22

A b o x c o n t a i n s 2 b l u e, 1 r e d b a l l s . W e r a n d o m l y

d r a w o n e b a l l t h e n p u t i t b a c k a n d a d d t w o b a l l s

o f t h e s a m e c o l o r o f t h a t b a l l i n t h e b o x . W e

r a n d o m l y d r a w a g a i n o n e b a l l, i f i t w a s r e d t h e n

{w h a t}^{'} s t h e p r o b a b i l i t y t h a t t h e f i r s t d r a w n b a l l

w a s b l u e ?

Commented by som(math1967) last updated on 17/Nov/22

50 % ?

Commented by Acem last updated on 17/Nov/22

{I t}^{'} s l e s s t h a n t h a t

Commented by som(math1967) last updated on 17/Nov/22

\frac{\frac{2}{3} \times \frac{1}{5}}{\frac{2}{3} \times \frac{1}{5} + \frac{1}{3} \times \frac{3}{5}} = \frac{2}{15} \times \frac{15}{5} = \frac{2}{5}

i . e 40 %

Commented by Acem last updated on 17/Nov/22

C o r r e c t S i r! T h a n k s!

Commented by som(math1967) last updated on 17/Nov/22

I m a d e a m i s t a k e i n t h e c a l c u l a t i o n

Commented by Acem last updated on 17/Nov/22

W h a t m a t t e r s i s t h e m e t h o d, a n d y o u r s w a s

100 % c o r r e c t! t h a n k y o u v e r y m u c h .

Commented by SLVR last updated on 18/Nov/22

G o o d s i r

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