Millisecond Forums

Hello,
I am new to inquisit and have just learned how to program a full task myself. I would like to be able to program a non-random selection of stimuli that reflects specific probabilities, but as far as I can tell there is the 'noreplace' or the 'noreplacenorepeat' option which randomly selects stimuli either with or without repeating. Is there any way to program a particular probability of a certain stimulus being presented for each trial or each block of trials?
The only other option I see is to hand-code my blocks to create the probabilities myself. As an example, I've pasted code below for the following: 70% chance of seeing stimulus 1, 10% chance of seeing stimulus 2, 10% chance of seeing stimulus 3, and 10% chance of seeing stimulus 4. Basically 7/10 trials are stimulus 1 and the rest are stimuli 2-4. My syntax seems to be wrong so I am wondering if this is even possible to do. 

<block practice>
/trials = [1=stimulus1; 2=stimulus2; 3=stimulus4; 4=stimulus1; 5=stimulus3; 6=stimulus1; 7=stimulus1; 8=stimulus1; 9=stimulus1; 10=stimulus1]
/pretrialpause = 500
</block>

Any help would be much appreciated!

Thanks,
Georgia