If a. Bathroom area is 8500 inches. And the tiles are 6 by 13ins, what's the least amount of tiles needed to cover area?

2 answers

6 * 13 = 78 square inches for each tile

8500 / 78 = 108.97 = 109 tiles
Unrealistic question.
Of course the minimum number of tiles would be obtained when the shape is as close to a square as possible, but we can't control the shape of the region based on the number of tiles. (The architect had decided the shape, perhaps it is not even rectangular )
Anyway .....
let the sides be x by y inches
xy = 8500
number of tiles = (x/6)(y/13) = xy/78 = 8500/78
= 108.9
.= 109 (using .= to mean appr =)

e.g. suppose 8500 = 100 by 85
using 100/6 tiles along the longer side = 16.66..
so let's say 17 tiles, with the last row to be cut
using 85/13 tiles along the longer side = 6.5 or 7 tiles, with the last row to be cut.
so we need 17x7 or 119 tiles.

Suppose we lay the tiles in alternate patterns, so we get 4 tiles to form a square of 19 by 19
then each grouping has a area of 361 in^2
so we need 8500/361 = 23.54 groupings
that is we need 24 groupings of 4 or 96 tiles
ok, so we would need (x/19) tiles along one side and (y/19) tiles
along the other side.

Assuming the area is square
then each side of the floor = √8500 = 92.195
92/6 = 15.33 , so we need 16 along that side
92/13 = 7.07 , so we need 8 along that side
number of tiles = 8x16 or 128

Assuming the area is made up of 170 by 50
using the longer side of tile along the longer side of the floor, we need 170/13 or 14 tiles, cutting needed for the last row

As you can see, more information is needed to get an actual answer