1.Donald finds a baseball card in his grandfather's attic.It shows a date so 1919 and depicts the then make up of the team of the Chicago Cubs.He shows the card to his friend, Francis.Both of them do not know if the card is authentic, nor if it can be considered 'mint' condition.A general requirement for the trading of baseball cards, comic books and other forms of collectibles.Donald agrees to sell the card to Francis for $18, the sum total of money that Francis has in his pocket.The parties subsequently discover that the card is in mint condition and is a rarity worth $18,000.Could Donald avoid the contract?On what grounds?Does assumption of the risk factor in here at all?What if Francis was a professional collectible trader and in 'good faith' guessed the worth of the card without doing further research.Would that change your answer?