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 the box.

Please solve this fast
it's too important now​

Answer 1

Total marbles = 9

Probability of drawing white marble = 2/9

=> Number of white marbles = 2

Probability of drawing blue marbles = 1/3 or 3/9

=> Number of blue marbles = 3

Now,

Number of red marbles = 9-5 = 4

Answer is 4 marbles

hope it helps!

Answer 2

Given,

The total number of marbles$\[ = 9\]$

The probability of getting a blue marble$\[ = \frac{1}{3}\]$

The probability of getting a white marble$\[ = \frac{2}{9}\]$

To find,

The number of red marbles in the box.

Solution,

Assume that the probability of a red ball is x.

Understand that the sum of probabilities of getting a ball is $\[1\].$

Therefore,

$\[\begin{array}{l} \Rightarrow \frac{1}{3} + \frac{2}{9} + x = 1\\ \Rightarrow x = 1 - \left( {\frac{1}{3} + \frac{2}{9}} \right)\\ \Rightarrow x = 1 - \left( {\frac{{1 \times 3}}{{3 \times 3}} + \frac{{2 \times 1}}{{9 \times 1}}} \right)\\ \Rightarrow x = 1 - \left( {\frac{3}{9} + \frac{2}{9}} \right)\end{array}\]$

Solve further,

$\[\begin{array}{l} \Rightarrow x = 1 - \frac{5}{9}\\ \Rightarrow x = \frac{{9 - 5}}{9}\\ \Rightarrow x = \frac{4}{9}\end{array}\]$

So, the number of red marbles is given as

$\[\begin{array}{l} \Rightarrow \frac{4}{9} \times 9\\ \Rightarrow 4\end{array}\]$

Hence, the number of red marbles in the box is $\[4.\]$