Let y be the number of yellow marbles

There are 11+7+y=18+y total marbles.

y/(18+y)=1/4.

4y=18+y

3y=18

y=6

There are 6 yellow marbles.

# Answer

6
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
In the jar, there are 7 blue marbles, 11 red marbles, and some yellow marbles. If the chance of randomly picking a yellow marble is 1/4, how many yellow marbles are there?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
6
In the jar, there are 7 blue marbles, 11 red marbles, and some yellow marbles. If the chance of randomly picking a yellow marble is 1/4, how many yellow marbles are there?
train