Answer:
The cost of one pound of the cheese is $4.2 .
The equation for direct variation is y = kx.
Where k is constant of variation .
Step-by-step explanation:
Let us assume that the pound of cheese be x.
Let us assume that the cost of cheese be y.
As given
The cost of cheese varies directly with the number of pounds purchased.
Thus
y = kx
Where k is the constant of variation.
Nola purchased 2.5 pounds of cheese for $10.50.
y = 10.50 , x = 2.5
Put in the y = kx
10.50 = 2.5k
k = 4.2
Her mother purchased 3 pounds of the same cheese for $12.60.
y = 12.60 , x = 3
Put in the y = kx
12.60 = 3k
k = 4.2
Therefore the constant of variation is 4.2 .
As given
One pound of cheese costs.
x = 1 , k = 4.2
Put in the y = kx
y = 1 × 4.2
= $4.2
Therefore the cost of one pound of the cheese is $4.2 .