if i wanted to be sure to take out a blue block,i would put in blank red blocks.

if the bag has 3 blue blocks

thank you for your help

I wouldn't.

If I wanted to be sure to take out a blue block, I would put in only blue blocks.

To ensure that you take out a blue block, you would put in blank red blocks. If the bag initially has 3 blue blocks, the process would work as follows:

1. Take out 3 blue blocks from the bag.
2. Insert 3 blank red blocks into the bag.
3. By doing this, you can be sure that the next block you pick will be a blue block, since all the original blue blocks were removed and replaced with blank red blocks.

In summary, to guarantee taking out a blue block from a bag that initially has 3 blue blocks, you would remove all the blue blocks from the bag and replace them with the same number of blank red blocks.