Question

Christina is packing different books into boxes. The paperback books weigh 0.8 pounds each. The hardcover books weigh 1.3 pounds each. Christina needs to pack the boxes so that there are at least 20 books in each box, but the boxes cannot weigh more than 30 pounds.

Identify Christina’s set of constraints.

Answer 1

P + H ≥ 20

P*0.8 lb + H*1.3 lb ≤ 30lb

Explanation:

Let's define H as the number of hardcover books.

Let's define P as the number of paperback books.

Now we have the restrictions:

"... so that there are at least 20 books in each box..."

Then:

P + H ≥ 20 (the total number of books per box is 20 or larger)

"...but the boxes cannot weigh more than 30 pounds."

P*0.8 lb + H*1.3 lb ≤ 30lb (the maximum weight that we can have in the box is 30 pounds)

Then the set of constraints is:

P + H ≥ 20

P*0.8 lb + H*1.3 lb ≤ 30lb

Notice that this system has a lot of possible solutions.

P = 20 and H = 0 is a solution

P = 21 and H = 0 is a solution.

P = 19 and H = 1 is a solution.

etc...