Answer:
Quantity of fuel is 24 L, based on the model S=2400/Q when S=100
Step-by-step explanation:
If the output power of the car remains constant, the speed would reduce as the masses increase, which is the shown in the observed data.
Hence S does NOT vary directly with the mass and quantity, but varies INVERSELY with the mass and fuel (which has a mass).
Many models are possible to fit the results. Product models with a single constant k
S(m,q) = kmq and S(m,q) = k/mq
do not fit both observation, hence rejected.
A possible model with two constants is shown below
S(m,q) = k1/m + k2/q..................(1)
1. m=220, q=30 => 80 = k1/220 + k2/30 ..........(2)
2. m=300, q=40 => 60 = k1/300 + k2/40 ..........(3)
Solve system (2) and (3) gives k1=0, k2 = 2400.
So it appears that the speed is independent of the mass (m) [unlikely], but inversely proportional to the quantity (q) of fuel, giving
S(q) = 2400/q
When speed = 100 km/h, and mass = 250 kg, substitute
100 = 2400/q => q=2400/100 = 24
