Answer:
Option B. 0.75 gallons is the right answer.
Step-by-step explanation:
Let the load of dishwasher used in house A = x gallons
Let the load of dishwasher used in house B is = y gallons
and similarly we assume for house C = z gallons
Now from the given question
On Friday amount of water used in all three houses = 17.5 gallons
From the table we will make the equation
x + 2y + 2z = 17.5-----(1)
For Saturday
2x + 3y + 4z = 31.5 ----(2)
For Sunday
2x + 2y + 3z = 24.75 -----(3)
By subtracting equation 3 from 2
y + z = 31.5 - 24.75 = 6.75 ------(4)
Equation (1) multiplied by 2 - equation (2)
2×(x + 2y + 2z) - (2x + 3y + 4z) = 17.5×2 - 31.5
y = 35 - 31.5 = 3.5
By putting y = 3.5 in the equation (4)
z = 6.75 - 3.5 = 3.25
By putting y = 3.5 and z = 3.25 in the equation (1)
x + 7 + 6.5 = 17.5
x = 17.5 - 13.5 = 4
Now the difference between load of dishwasher that uses least water and the most.
x - z = 4 - 3.25 = 0.75 gallons
Option B is the right answer.
