Question

A bag contains 5 white balls and some black balls. If the probability of drawing a black ball from the bag is twice the probability of drawing a white ball then find the number of black balls.​

Answer 1

Answer:

white balls = 5

let black balls = x

total no. of balls = x+5

P(black ball) =2×P(white ball)

no. of black balls = 2× no. of white balls

total no. of balls. total no. of balls

x = 2× 5

x+5 x+5

x = 10

x+5 x+5

x(x+5) = 10(x+5)

x² + 5x = 10x + 50

x² + 5x - 10x - 50 = 0

x² - 5x - 50 = 0

x² - ( 10-5)x -50 = 0

x² - 10x + 5x - 50 = 0

x(x-10) + 5(x-10) = 0

(x-10) (x+5) = 0

x-10 = 0 or x+5 = 0

x = 10 or x = -5 (balls can never be negative) Hence, no. of black balls = 10

Step-by-step explanation:

here is your answer