Question

There are red, yellow and green marbles in a jar. How many marbles are yellow in colour? Given:

a. Probability of finding a red marble is the same as that of a green marble but is double that of finding a yellow marble.

b. There are 6 green marbles in the jar.

Answer 1

Answer:12

Step-by-step explanation:

Given that

No. of green marbles =6

And probability is same for red marbles. It means no. of red marbles= no. of green marbles= 6

Let no. of yellow marbels =x

So total no. of marblels are =6+6+x

Probability of finding yellow marbles = $\frac{x}{6+6+x}$

Probability of finding green marbles = $\frac{6}{6+6+x}$

It is given that probability of finding green marbles is double to the probability of yellow marbles

So

$2*\frac{x}{6+6+x}=\frac{6}{6+6+x}$

⇒36+36+6x=12x+12x+2x²

⇒72+6x=24x+2x²

⇒2x²+18x-72=0

⇒x²+9x-36=0

⇒(x-12)(x-+3)=0

so x=12 (x= -3 not possible)

so there are 12 yellow marbles