Final answer:
The percentage gain in mass of the potato is calculated by dividing the gain in mass (25 g) by the initial mass (25 g) and multiplying by 100%, resulting in a 100% gain in mass.
Step-by-step explanation:
To calculate the percentage gain in mass of the potato, you first find the difference in mass, then divide that by the initial mass, and finally multiply by 100 to get the percentage. The initial mass of the potato was 25 g, and after being in water for 15 minutes, its final mass was 50 g. So the gain in mass is 50 g - 25 g = 25 g.
Next, we calculate the percentage increase relative to the original mass:
Percentage gain = (Gain in mass / Initial mass) x 100%
Percentage gain = (25 g / 25 g) x 100% = 100%
Therefore, the percentage gain in mass of the potato is 100%.