how many envelopes can be made out of a sheet of paper 3m 24cm by 1m 72cm,if each envelope requires a piece of paper of side 18cm by 12cm?

1 answer

the sheet of paper is
324 cm by 172 cm
The tempation is to say:
area of whole paper = 55728 cm^2
area of 1 envelope = 216
so we have 55728/216 or 258 envelopes.
BUT, not so fast .....

If we lay the length of the envelope along the long side of the large sheet, we can get 324/18 or 18 along that side
the number of envelopes along the short side is 172/12 = 14 1/3
but we need whole numbers,
so number of envelopes = 18x14 or 252
with some waste of paper.

If we lay the width of the envelope along the long side of the large sheet, we can get 324/12 or 27 of them, but then along the other side we would get 172/18 or 9.55..
Again we could only get 9 rows, for a number of envelopes of 27x9 = 243

The largest number of envelopes is 252