Question

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

Answer 1

$\huge \mathtt { \underline{ \green{Correct \: Question?}}}$

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

$\huge \mathtt { \underline{ \green{Solution:- }}}$

$\large { \underline{ \underline{ \sf { \red{ Given:- }}}}}$

• A bag contains 15 white and some black balls .

$\large { \underline{ \underline{ \sf { \blue{ To \: prove:- }}}}}$

• Number of black balls in the bag.

$\large { \underline{ \underline{ \sf { \orange{ Directions:- }}}}}$

$\bf \purple{Let:- }$

• Numberof black balls = x

$\bf \purple{So \: now:- }$

• Probability of drawing a white ball

$\implies\frac{15}{15 + x}$

• Probability of drawing a black ball

$\implies\frac{x}{15 + x}$

$\bf \purple{According \: To \: Question:- }$

$\leadsto \frac{x}{x + 15} = \frac{3 \times 5}{15 + x}$

$\leadsto x = 3 \times 15$

$\leadsto45$

$\pink { \boxed{ \sf{Therefore, the \: nunber \: of \: black \: balls \: is \: 45}}}$