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?
Let's think step by step.
6
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.

.

Therefore, the answer is 6