A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four times that of a red ball. Find the number of blue balls in the bag.

Solution

Number of red balls in the bag = 5
Let number of blue balls in the bag = x
Now, total number of balls in the bag = x + 5
i.e., n( S) = n + 5
(i) Let ‘A’ be the favourable outcomes of getting blue balls, then
n( A) = x
Therefore,
P(A) = $fraction numerator straight n left parenthesis straight A right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x over denominator x plus 5 end fraction$

(i) Let 'B' be the favourable outcomes of getting red balls, then
n(B) = 5
Therefore,
P(B) = $fraction numerator straight n left parenthesis straight B right parenthesis over denominator straight n left parenthesis straight S right parenthesis end fraction equals fraction numerator x over denominator x plus 5 end fraction$
According to question :
P(A) = 4 P (B)
$rightwards double arrow space space space space fraction numerator straight x over denominator straight x plus 5 end fraction equals 4 open parentheses fraction numerator 5 over denominator straight x plus 5 end fraction close parentheses rightwards double arrow space space straight x space equals space 20$
Hencem the number of blue balls in the bag is 20.

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Real Numbers

A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four times that of a red ball. Find the number of blue balls in the bag.

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The probability of an event that is certain to happen is Such an event is called _.

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For Daily Free Study Material Join wiredfaculty

Real Numbers

A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball from the bag is four times that of a red ball. Find the number of blue balls in the bag.

Some More Questions From Real Numbers Chapter

The probability of an event that is certain to happen is ________ Such an event is called _________.

The sum of the probabilities of all the elemen-tary events of an experiment is ______.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

The probability of an event that is certain to happen is Such an event is called _.