Math, asked by ananyasinha60901, 9 days ago

A box contains 5 red and k blue balls. A ball is selected at random from the box. If the probability of selecting a blue ball is 23, find the value of k ?

Answers

Answered by 192529evangelene
1

Answer:

10

Step-by-step explanation:

Let the number of blue balls =x  

Total number of balls =5+x  

Probability for a red ball = x+5  

Probability for a blue ball = 5+x

 

According to the question  

 

5+x​

=2(x+5)⇒x=10  

∴ Number of blue balls =10.

Answered by tennetiraj86
2

Step-by-step explanation:

Given :-

A box contains 5 red and k blue balls. A ball is selected at random from the box. The probability of selecting a blue ball is 23.

Correction :-

The probability of selecting a blue ball is 2/3

To find :-

Find the value of k ?

Solution :-

Given that

Number of red balls in a box = 5

Number of favourable outcomes to red ball = 5

Number of blue balls in the box = k

Number of favourable outcomes to blue ball = k

Total number of all balls in the box = (5+k)

Total number of all possible outcomes = (5+k)

We know that

The probability of getting an even P(E) =

Number of favourable outcomes / Total number of all possible outcomes

Now,

Probability of getting a blue ball = P(B)

=> Number of favourable outcomes to blue ball / Total number of all possible outcomes

=> P(B) = k / (5+k)

According to the given problem

Probability of getting a blue ball = 2/3

=> k / (5+k) = 2/3

On applying cross multiplication then

=> 3k = 2(5+k)

=> 3k = 10+2k

=> 3k-2k = 10

=> k = 10

Therefore, k = 10

Number of blue balls = 10

Answer :-

The value of k for the given problem is 10

Note :-

If the Probability of getting a blue ball = 23 then we get the value of k as negative ,So it is not possible for the number of blue balls ,it must be a positive number.

Used formulae:-

→ The probability of getting an even P(E) =

Number of favourable outcomes / Total number of all possible outcomes

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