You conclude that the sucrose solution is hypotonic to the potato cells.
Step-by-step explanation:
A solution is said to be hypotonic with respect to other solution if its concentration is less than the other solution to which it is compared.
A concentration of solvent molecule in a hypotonic solution is higher than hypertonic solution so solvent moves from hypotonic to hypertonic solution due to osmosis.
The increase in weight of potato shows that it has gained water i.e. the water has entered from the sucrose solution to cells. So, the sucrose solution is hypotonic to the cell sap.