A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball is double

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27 Apr 2013 Probability

A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball is double that of a red ball, Number of blue ball is..

OPtion

1) 22
2) 18
3) 15
4) 13
5) 12
6) 10
7) 8
8) 7
9) 6
10) None of these

Solution

let number of blue ball = x
Given
Probability(Blue ball)= 2*Probability(Red ball)
(x/(5+x))=2(5/(x+5))
solve x=10
option 6

Correct Option: 6 Best Solution (9)

KAUSHAL KASHYAP   11 years AGO

no of Red balls=5
let no of Blue balls=x
p(red)=5/(5+x )
therefore p(blue)=10/(5+x)
no of blue balls=10

Like? Yes (58) | No (29)  

sanjay singh   11 years AGO

let no.of blue balls=x
toal no.of balls=5+x
p(b)=x/5+x
p(r)=5/5+x
now,
p(b)=2p(r)
solving we get x=10.

Like? Yes (36) | No (17)  

M Rakesh   11 years AGO

let n be no. of blue balls,
then n/n+5=2(5/n+5)
solving n=2*10;
n=10
so blue balls is 10

Like? Yes (27) | No (15)  

Abhishek Mishra   11 years AGO

let the No of balls is x.
given
2*(5/5+x)=x/x+5
hence x=10.

Like? Yes (26) | No (21)  

tejaswini g   11 years AGO

let blue balls =x
red balls=5
so total balls=x+5
p(getting blue balls)=2*(getting red balls)
x/(x+5)=2*(5/(x+5))
x=10

Like? Yes (18) | No (13)  

shivendra pratap singh   11 years AGO

red balls=5
blue balls=x
p(red)=5\(5+x)
p(blue)=x\(5+x)

p(blue)=2[p(red)]
x\(5+x)=10\(5+x)
so x=10 i.e. no of blue balls is 10

Like? Yes (20) | No (16)  

jitendra Gangil   11 years AGO

let\'s blue balls be x.
then by according to q
(x/x+5)=(2*5/x+5)
on solving we get
x=10(blues balls)

Like? Yes (15) | No (12)  

jitendra singh   11 years AGO

10 balls

Like? Yes (16) | No (14)  

Vinay Sipani    11 years AGO

x / (x + 5) = 2*5 / (x + 5)
=> x = 10

Like? Yes (14) | No (14)