ASK YC:Advertising Revenue

Hello all, I've been looking for an answer to a question, but it is one that I have not been able to find. In preparing a Business Plan, I am looking at the economics of justifying an advertising revenue model. But the only numbers I am able to come up with amount to $94 a month from 125,000 unique visitors a month. Any suggestions or help would be appreciated. How can you have a viable company on $94 a month when you have 125,000 people visiting it?