a bag contains 5 red balls and some blue balls if the probability of drawing a blue ball - Maths - Probability

Question

a bag contains 5 red balls and some blue balls if the
probability of drawing a blue ball is double that of red ball,
determine the number of blue ball in the bag

Robin · Accepted Answer

LET THE NO OF BLUE BALLS BE X
NO OF RED BALLS = 5
TOTAL NO OF BALLS = NO OF BLUE BALLS + NO OF RED BALLS
= X + 5
PROBABILITY OF GETTING BLUE BALL = X / X + 5
PROBABILITY OF GETTING RED BALL = 5/ X +5
ACCORDING TO THE QUESTION,
X / X + 5 = 2 * 5 / X + 5
CANCELLING X+5 FROM BOTH TERMS AS THEY ARE COMMON
X = 10
SO, THERE ARE 10 BLUE BALLS IN THE BAG

a bag contains 5 red balls and some blue balls . if the probability of drawing a blue ball is double that of red ball, determine the number of blue ball in the bag