Mojo Beverage placed the following advertisement in a local newspaper on 25 January:

Come one,come all! Fishermen and women of Lake Tranquil.We are offering to pay $100,000 to any person who catches Lord Harry,a trout which we have tagged and released into the lake.

The following day was the Australia Day holiday .Lake Tranquil was crowded with people fishing both from the bank and from boats.At about lunch time,a rumour spread among the people on the bank that there had been an error in the advertisement :that the true amount should have been $1,000 and that Mojo Beverage had announced that the prize would be the lower amount.The rumour was in fact true.Ben heard this rumour from the stranger fishing beside him,minutes before catching Lord harry.A Mojo Beverage representative was on hand to certify the catch before Lord Harry was released back into the lake,but did not say anything about the amount of the prize.

Ben is claiming that Mojo Beverage owes him $100,000.

Advise Mojo Beverage,explaining applicable legal principles and citing relevant authorities.