The company's management is finalizing the marketing promotion program and offers to hold a draw for your company's expensive products. The price of such a product is 1000 dollars. The conditions for participation are as follows. If a purchase of goods worth $ 300 per month is made, then the probability of winning is 30%; if for 500 dollars a month, then the probability of winning is 40%;if for 700 dollars, then 50%.Which option is more preferable for the buyer? Bring the calculations.