metallicafan wrote:
On the number line above, the segment from 0 to 1 has been divided into fifths, as indicated by the large tick marks, and also into sevenths, as indicated by the small tick marks. What is the LEAST possible distance between any two of the tick marks?
A. 1/70
B. 1/35
C. 2/35
D. 1/12
E. 1/7
Attachment:
GMAT_PS_PREP_T2_108.png
Each of 1/5th, 2/5th,3/5th, 4/5th, 1..... and 1/7th, 2/7th, 3/7th, 4/7th, 5/7th, 6/7th, 1 are the divisions can be put up on the number line however it is very time consuming to keep checking the placements and calculate the difference hence, instead of the number line being from 0 to 1. For the ease of calculation we can stretch the number line from 0-35. (Why 35? Because the LCM of 5 and 7 will help break each tick on the number line into a whole number.
The number line should look something like this
0----5--7--10---
14 15----
20 21---25--28-30
The lowest difference between both 14 and 15 as well as 20 and 21 is 1 however since the number line is based on 35 total stretch, the least distance is 1/35
Hope this helps a little