Problem Solving

GMAT Prep problem

klmehta03 wrote:GMAT Prep problem

I hope it's not an offence to post an original screen-shot from a GMATprep; anyway....


A fifth is 1/5 of something, and a seventh is 1/7 of something. The four large ticks between 0 and 1 read 1/5, 2/5, 3/5, and 4/5; whereas the six small ticks between 0 and 1 read 1/7, 2/7, 3/7, 4/7, 5/7, and 6/7. The LCD of all fractions is 35; hence otherwise the four large ticks between 0 and 1 read 7/35, 14/35, 21/35, and 28/35; whereas the six small ticks between 0 and 1 read 5/35, 10/35, 15/35, 20/35, 25/35, and 30/35. The smallest difference between a large tick and a small tick is clearly the difference between [spoiler]21/35 and 20/35, which is 1/35.

Take B[/spoiler]