Answer:
Please check the explanation.
Explanation:
We know that when 'y' varies directly with 'x', the equation becomes
y ∝ x
y = kx
where 'k' is called the constant of proportionality.
From the table, it is clear that 'y' varies directly with 'x'
Let us check the value of k for all the points
k = y/x
For the point (130, 9.10)
For the point (145, 10.15)
- k = y/x = 10.15 / 145 = 0.07
For the point (150, 10.50)
- k = y/x = 10.50 / 150 = 0.07
For the point (185, 12.95)
- k = y/x = 12.95 / 185 = 0.07
Thus, the value of proportionality constant is same.
i.e. k = 0.07
Determining the cost of 21 feet of the wire
- And need 21 feet of the wire.
21 feet = 252 inch
Using the equation
y = kx
- where y represents the cost and x represents the length in inches
Thus, the cost of 252-inch wire will be:
y = kx
substituting k = 0.07, and x = 252
y = 0.07 × 252
y = 17.64 Dollars
Thus, the cost of 21 feet wire will be: 17.64 Dollars
Determining the cost of 15 yards of the wire
- Emily needs 15 yards of the wire.
15 yards = 540 inches
Using the equation
y = kx
- where y represents the cost and x represents the length in inches
Thus, the cost of 15 yards of wire will be:
y = kx
substituting k = 0.07, and x = 540
y = 0.07 × 540
y = 37.8 Dollars
Thus, the cost of 15 yards of wire will be: 37.8 Dollars