The cost (y), in dollars, to purchase x dozen doughnuts from Bakery A and Bakery B can be found using the equations shown in the table.

 
Bakery Cost ,begin bold,(,end bold,y) A y equals 9 x B y equals 8 x
Question
Choose ,begin emphasis,all,end emphasis, of the statements that are true based on the equations given. 
Answer options with 4 options
A.
Bakery A charges about 8 cents more per doughnut than Bakery B.
B.
The cost of 2 dozen doughnuts is 2 dollars more at Bakery A than Bakery B.
C.
Bakery A charges $1.33 per doughnut and Bakery B charges $1.50 per doughnut.
D.
Bakery A charges $0.75 per doughnut and Bakery B charges $0.67 per doughnut.

1 answer

To evaluate the statements based on the cost equations for both bakeries, we need to determine the cost per doughnut for each bakery.

  1. Bakery A’s cost equation:
    \(y = 9x\)
    This means the cost for \(x\) dozen doughnuts is \(9\) dollars per dozen. Since there are \(12\) doughnuts in a dozen, the cost per doughnut for Bakery A is: \[ \text{Cost per doughnut at Bakery A} = \frac{9 \text{ dollars}}{12 \text{ doughnuts}} = \frac{9}{12} = 0.75 \text{ dollars or } 75 \text{ cents} \]

  2. Bakery B’s cost equation:
    \(y = 8x\)
    This means the cost for \(x\) dozen doughnuts is \(8\) dollars per dozen. The cost per doughnut for Bakery B is: \[ \text{Cost per doughnut at Bakery B} = \frac{8 \text{ dollars}}{12 \text{ doughnuts}} = \frac{8}{12} = \frac{2}{3} \text{ dollars or } 66.67 \text{ cents} \]

Now, let's examine each statement:

A. Bakery A charges about 8 cents more per doughnut than Bakery B.

  • Cost per doughnut at Bakery A: \(75\) cents
  • Cost per doughnut at Bakery B: \(66.67\) cents
  • Difference: \(75 - 66.67 = 8.33\) cents
  • True.

B. The cost of 2 dozen doughnuts is $2 more at Bakery A than Bakery B.

  • Cost for 2 dozen at Bakery A: \(y = 9(2) = 18\) dollars
  • Cost for 2 dozen at Bakery B: \(y = 8(2) = 16\) dollars
  • Difference: \(18 - 16 = 2\) dollars
  • True.

C. Bakery A charges $1.33 per doughnut and Bakery B charges $1.50 per doughnut.

  • We calculated that Bakery A charges \(0.75\) (or \(75\) cents) per doughnut and Bakery B charges \(0.67\) (or \(66.67\) cents) per doughnut.
  • Both values are incorrect.
  • False.

D. Bakery A charges $0.75 per doughnut and Bakery B charges $0.67 per doughnut.

  • We calculated that Bakery A charges \(0.75\) (or \(75\) cents) per doughnut and Bakery B charges approximately \(0.67\) (or \(66.67\) cents) per doughnut.
  • True.

So, the true statements are:

  • A
  • B
  • D