Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND EditionWhat is the maximum number of \(1\frac{1}{4}\) foot pieces of wire that can be cut from a wire that is 24 feet long?
(A) 11
(B) 18
(C) 19
(D) 20
(E) 30
1 1/4 is equal to 5/4
The number of wire pieces = Total length/ Lenth of one Piece = 24/(5/4) = (24*4)/5 = 96/5.
Now the nunber of pieces has to be an integer value and it cannot be more than 96/5 since we have run out of material. Can be only less. So rounding down 96/5 to an interger gives 95/5 = 19.
During the solution it would help to realize that 96/5 lies between 95/5 and 100/5 ie 19 < 96/5 < 20. Putting this in words : We ran out of material for the 20th piece, we have material enough for 19 pieces only.
I believe that this would be a 500-600 level question. It is relatively simple. The key here is that if you can get yourself to knock such questions out in a minute, you save the extra minute for a harder question to boost your score!