A bag contain 5 red balls and some blue balls. If the probability of drawing a blue ball from the ba

M4maths Previous Puzzles

03 May 2016 Find the number of ball

A bag contain 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four time that of a red ball, then find the number of blue balls in the bag.

OPtion

1) 10
2) 12
3) 15
4) 20
5) 22
6) 25
7) 30
8) 35
9) 40
10)None of these

Solution

Number of red balls = 5
Let the number of blue balls = x
Therefore Total number of balls in the bag = (5+x)
According to the question
P(blue ball) = 4 P(red ball)
x/(5+x) = 4(5/(5+x))
x = 20
Option 4)

Correct Option: 4 Best Solution (11)

MRITUNJAY   8 years AGO

no. of red balls= 5
let no of blue balls= x

the probability of drawing a blue ball from the bag is four times that of a red ball. 

Prob. of red ball= 5 / x+5

Blue ball= x/ x+5
A/c

x / x+5 = 4 * 5 / x+5

so x= 20 number of blue ball is 20
Option 4

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abhishek chaubey   8 years AGO

Let no. of blue balls be x
So P(B) = 4* P(R)
x/(5+x) = 4* 5/ (5+x)
on solving the above equation x= 20

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shubham sethiya   8 years AGO

probability of red ball is 5/5+b
probability of blue ball is b/5+b
given condition is 4*5/5+b=b/5+b

so it gives b =20

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RAHUL KUMAR   8 years AGO

Let no. of red balls= 5; blue= x
the probability of drawing a blue
ball from the bag is four times that of a red ball.
Prob. of red ball= 5 / x+5
Blue ball= x/ x+5
x / x+5 = 4 * 5 / x+5

so x= 20 blue balls.
option (4)

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Devendra Marghade   8 years AGO

If blue balls are 'x' , then
Probability of drawing blue balls=x/(5+x) and
Probability of drawing red balls=5/(5+x)
Given probability of drawing blue balls is 4 times that of red balls, so x/(5+x)=4*5/(5+x) , x=20
Option 4)

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neha gupta   8 years AGO

Let number of blue balls = x
then total balls = 5+x
P(B) = 4 P(R)
x/5+x = 4(5/5+x)
solving this we get
x = 20
so number of blue balls = 20

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SHIVALINGAPPA SHIVPUTRAPPA NIMBAL    8 years AGO

because red ball probability is 5 so blue ball probability 4*5 so 20

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Mukund Manohar   8 years AGO

probability of red ball = 5/x+5
probability of blue ball = x/x+5
x/x+5 = 4*(5/(x+5))
x = 20

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ABHINAV PUSHPAM   8 years AGO

Let no. of red balls= 5; blue= x

the probability of drawing a blue ball from the bag is four times that of a red ball.�

Prob. of red ball= 5 / x+5

Blue ball= x/ x+5

x / x+5 = 4 * 5 / x+5

x+5 gets canclled

so x= 20 blue ball.

Option 4)

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Kunal nemu   8 years AGO

let the number of blue ball = x
given
probability(blue ball) = 4*probability(red ball)
x/(5+x) = 4* 5/(5+x)
x = 20
option 4

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sumant kumar   8 years AGO

let no. of red balls=5, blue=x
the probability of drawing a blue ball from the bag is 4 times that of a red ball.
probability of red ball=5/x+5
blue ball= x/x+5
x/x+5= 4 * 5/x+5
x=20

Like? Yes (1) | No (1)