Final answer:
The Smiths and Jones encountered a bilateral mistake with an incorrect land survey, making their contract voidable. Issues like this can arise due to irregular property lines in the metes and bounds system, where accurate property titles are crucial.
Step-by-step explanation:
The situation described, where both parties to a contract relied on an incorrect survey of land, falls under the category of a bilateral mistake. This means that both the Smiths and Jones were mistaken about a basic assumption on which the contract was made. In this case, the size of the property was understood to be 1.5 acres instead of its actual size, 1 acre. As such, the contract is considered voidable because of the mutual error.
To provide some context, the metes and bounds system of property delineation, which often results in irregular property shapes and sizes, can lead to confusion and potentially incorrect land surveys. This may contribute to situations like the one involving the Smiths and Jones. Additionally, an accurate survey is essential for a property title, which needs to reflect the true dimensions and acreage of the land when it is transferred or sold.