at least 40 pounds of fertilizer is needed to adequately cover your backyard. let f= the amount of fertilizer needed
144 Get 160 to be safe.
72 Get 80 to be safe.
4.5 pavers will cover 1 sq foot. So 4.5 x 360 =1620 pavers
72 Get 80 to be safe.
144.63 pavers
101.25 pavers
153.84 pavers
you would need 10 pavers to cover this area if the pavers are 1x1 ..most pavers are not this large they are usually 2x4. I would recommend buying a couple of extra pavers so that you can have cuts instead of all the pavers being the same size.
In theory the answer is 240 tiles but this assumes that the area is "well behaved" and, if not, that you are prepared to use all the offcuts to fill bits in mosaic-style. A shape which in 17 inches wide, for example, will require a lot more pavers.
You would need 320 pavers to cover 160 square feet with 6x9 pavers, assuming each paver covers 0.5 square feet.
Assuming the question is about pavers that are 12 inch x 12 inch, then each paver covers 1 sq foot and so 150 pavers would be required. However, this also assumes that there is no wastage at all and that there are no breakages.