Jack compute the cost of covering the floor of his dining room with tile. the floor measures 15 feet 8 inches by 10 feet 4 inches. each tile covers 1 square foot. a box of 20 tiles costs $49.80. how many boxes will he need to buy and what is the cost?
a. jack will need 7 boxes; the cost is $348.60
b. jack will need 8 boxes; the cost is $398.40
c. jack will need 9 boxes; the cost is $448.20

C. Jack will need 9 boxes; the cost is $448.20

The area of the floor is the product of its length and width:

... A = LW = (15 2/3 ft)·(10 1/3 ft) = (150 +5 + 6 2/3 + 2/9) ft² = 161 8/9 ft²

8 boxes will cover 8·(20 ft²) = 160 ft², so is not enough tile.

Jack will need 9 boxes.

The cost of 9 boxes of tile is ...

... (9 boxes)·($49.80/box) = $448.20

The cost is $448.20.

Comment on this solution

The floor area calculation assumes tiles can be cut and fit without any issues. More likely, 11 rows of 16 tiles would be used, for a total of 176 tiles. Fortunately, 9 boxes contain 180 tiles, so 9 boxes is enough.