Question

It takes 6 slices of bread, 9 oz of cheese, and 2 oz of butter tomake three grilled-cheese sandwiches. What is the cost per sandwichif bread (18 slices) costs $1.90, 1 lb of cheese costs $2.49, and1/2 lb of butter costs $1.29?a. $.78b. $4.87c. $2.12d. $1.62

Answer 1

Step 1: Write the equivalence of each unit

`\begin{gathered} 1lb\Rightarrow16\text{ oz} \\ 1\text{ lb of cheese }\Rightarrow\text{ 16 oz of che}ese \\ (1)/(2)\text{ lb of butter }\Rightarrow\text{ 8 oz of butter} \end{gathered}`

Step 2: Calculate the cost of producing 3 grilled-cheese sandwiches

`\begin{gathered} 18\text{ slices of bread cost \$1.90} \\ 1\text{ slice will cost x} \\ \Rightarrow x=(1.90)/(18) \\ 6\text{ slices of bread will cost=}(1.90)/(18)*6=\text{ \$0.63} \end{gathered}`
`\begin{gathered} 1\text{ lb of cheese cost \$2.49 } \\ \text{ Since 1 lb is equal to 16 oz} \\ 16\text{ oz of cheese cost \$2.49} \\ 1\text{ oz of cheese will cost \$x} \\ \Rightarrow\text{ \$x=}(2.49)/(16)\text{ } \\ 9\text{ oz will cost }\Rightarrow\text{ }(2.49)/(16)*9=\text{ \$1.40} \end{gathered}`
`\begin{gathered} (1)/(2)\text{ lb of butter cost \$1.29} \\ \text{ This implies } \\ 8\text{ oz of butter will cost \$1.29} \\ 1\text{ oz of butter will cost \$x} \\ \Rightarrow\text{ \$x =}(1.29)/(8) \\ 2\text{ oz will then cost =}(1.29)/(8)*2=\text{ \$0.32} \\ \end{gathered}`

From the above calculations we can calculate the cost of producing three grilled-cheese sandwiches as

`0.63+1.40+0.32=\text{ \$2.35}`

Thus, the cost per sandwich is given as

`(2.35)/(3)=\text{ \$0.78}`

Hence, the cost per sandwich is $0.78

Option A is the right answer