Advertisements
Advertisements
प्रश्न
A bag contains 12 blue balls and x red balls. If one ball is drawn at random if 8 more red balls are put in the bag, and if the probability of drawing a red ball will be twice that it will be a red ball, then find x.
उत्तर
Sample space = 12 + x
n(S) = x + 12
8 more red balls are added
Sample space = x + 12 + 8 = x + 20
Number of red balls = x + 8
Probability of drawing red ball = `(x + 8)/(x + 20)`
By the given condition
`(x + 8)/(x + 20) = 2(x/(x + 12))`
(x + 8)(x + 12) = 2x(x + 20)
x2 + 20x + 96 = 2x2 + 40x
x2 + 20x – 96 = 0
(x + 24)(x – 4) = 0
x = − 24 or x = 4
The value of x = 4 ...(Number of balls will not be negative)
The probability of getting red balls = `(x/(x + 12))`
= `4/16`
= `1/4`
APPEARS IN
संबंधित प्रश्न
A bag contains 5 red balls, 6 white balls, 7 green balls, 8 black balls. One ball is drawn at random from the bag. Find the probability that the ball drawn is white
In a box there are 20 non-defective and some defective bulbs. If the probability that a bulb selected at random from the box found to be defective is `3/8` then, find the number of defective bulbs
The king and queen of diamonds, queen and jack of hearts, jack and king of spades are removed from a deck of 52 playing cards and then well shuffled. Now one card is drawn at random from the remaining cards. Determine the probability that the card is a queen of red card
Some boys are playing a game, in which the stone thrown by them landing in a circular region is considered as win and landing other than the circular region is considered as a loss. What is the probability to win the game? (π = 3.14)
In a game, the entry fee is ₹ 150. The game consists of tossing a coin 3 times. Dhana bought a ticket for entry. If one or two heads show, she gets her entry fee back. If she throws 3 heads, she receives double the entry fees. Otherwise, she will lose. Find the probability that she gets double entry fee
Which of the following is incorrect?
The probability a red marble selected at random from a jar containing p red, q blue and r green marbles is
A page is selected at random from a book. The probability that the digit at units place of the page number chosen is less than 7 is
The probability of getting a job for a person is `x/3`. If the probability of not getting the job is `2/3` then the value of x is
If a letter is chosen at random from the English alphabets {a, b, …, z}, then the probability that the letter chosen precedes x
