A bag contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is `2/5,` find the number of red 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 a red ball, find the number of 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 a red ball, find the number of 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 a red ball, find the number of 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 a red ball, find the number of blue balls in the bag.

A bag contains 6 red balls and some blue balls. If the probability of drawing a blue ball from the bag is twice that of a red ball,find the number of 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 a red ball, Find the number of 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 a red ball,find the number of blue balls in the bag.

A bag contains 15 white balls and some black balls. If the probability of drawing a black ball is thrice that of a white ball, find the number of black balls in the bag.

A bag contains 15 white balls and some black balls. If the probability of drawing a black ball is thrice that of a white ball, find the number of black balls in the bag.