The probability of picking a brown marble, not replacing it and picking up another brown marble would be 1/18
So firstly you want to find out the total of all the marbles, in this case the total number of marbles is 19.
Now since we're dealing with probability we'd want to convert our fraction of interest 1/19 (we're interested in the 1 brown marble) into a percentage
doing so gets us 5%
Picking another brown marble has a probability of 0% since we only have 1 brown marble in the first place
