Question

A box contains 9 marbles in that, some are blue, some are white and remaining are red. If the probability that blue marble is drawn is 1/3 and that of white marble drawn is 2/9 ,then find the number of red marbles in a box

it is urgent
​write only correct answer

Answer 1

blue = 1/3 x 3/3 = 3/9 so there are 3 marbles

white = 2/9 so there are 2 marbles

red =9- (3+2) = 4.

Answer 2

$\large\underline{\sf{Given- }}$

A box contains 9 marbles in that, some are blue, some are white and remaining are red. If the probability that blue marble is drawn is 1/3 and that of white marble drawn is 2/9.

$\large\underline{\sf{To\:Find - }}$

Number of red marbles in a box

$\large\underline{\sf{Solution-}}$

Given that,

Total number of marbles = 9

Let assume that

Number of blue marbles = b

Number of white marbles = w

Number of red marbles = r

$\rm\implies \:b + w + r = 9$

Now, It is given that

$\rm \: Probability(getting\:blue\:marbles) = \dfrac{1}{3}$

$\rm \: \dfrac{b}{9} = \dfrac{1}{3}$

$\rm\implies \:b \: = \: 3 - - - - (1)$

Also, given that

$\rm \: Probability(getting\:white\:marbles) = \dfrac{2}{9}$

$\rm \: \dfrac{w}{9} = \dfrac{2}{9}$

$\rm\implies \:w \: = \: 2 - - - - (2)$

So, as we have

$\rm \:b + w + r = 9$

$\rm \:2 + 3 + r = 9$

$\rm \: r = 9 - 3 - 2$

$\rm\implies \:r \: = \: 4$

So, Number of red balls = 4

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Formula Used

$\sf \:Probability \: of \: an \: event =\dfrac{Number \: of \: favourable \: outcomes}{Total \: number \: of \: outcomes \: in \: sample \: space}$

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ADDITIONAL INFORMATION :-

The sample space is the collection of all possible outcomes associated with the random experiment.

The probability of elementary event always lies between 0 and 1 including 0 and 1.

The probability of sure event is 1.

The probability of impossible event is 0.

P(A) + P(A') = 1