damn it scotty!!!

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damn it scotty!!!

by tdadic84 » Thu May 28, 2009 10:40 am
from gmatclub.com


Scott has a 100 page book. He puts a dot on Page 1, and then on every 7th and 8th page after that. How many page DO NOT have a dot on it..


I got 75...but the long method of writting it all down...what is another approach?
Source: — Problem Solving |

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by scoobydooby » Thu May 28, 2009 11:05 am
pages dotted: 1; 7/8; 15/16; 23/24; 31/32.......
=> after the 1st page both sides of the 8th page
100/8 gives 12 remainder 3, so there are 12 sets of 8th pages both sides of which are dotted

so total dotted pages: 1+12*2=25
undotted: 100-25=75

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by PAB2706 » Thu May 28, 2009 11:07 am
Scotty doesn't know.. Scotty scotty scotty...

:lol:

I got 72

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by PAB2706 » Thu May 28, 2009 11:15 am
oh freak I did a silly mistake... I guess I am excited bout fiona... :lol:

75 is right... Scooby's way is good...