Final answer:
The height of the first floor, based on the difference in water pressure and the density of the water, calculates to be 3.06 meters. There seems to be an issue with the provided options because 3.06 meters isn't listed.
Step-by-step explanation:
To find the height of the first floor, we need to calculate the difference in water pressure between the ground floor and the first floor, and use the formula that relates pressure difference to height, density, and gravitational acceleration.
The pressure difference (ΔP) is the pressure at the ground floor minus the pressure at the first floor: ΔP = Pground - Pfirst floor = 50000 Pa - 20000 Pa = 30000 Pa.
Using the equation P = hρg, where P is pressure, h is height, ρ (rho) is the density of water, and g is acceleration due to gravity (approximately 9.81 m/s2), we can rearrange the formula to solve for height: h = P / (ρg).
Therefore, the height of the first floor is h = 30000 Pa / (1000 kg/m3 × 9.81 m/s2) = 3.06 meters, which is not an option provided in the question. There may be an error in the question itself or in the provided options.