<p>I am posting this for a friend who's CC account isn't working. I'm really rusty on SAT math so I was wondering if you guys could help. </p>
<p>Chairs ready for every shipment at the Northern Chair factory come down a ramp in a single file. Inspector A checks every 3rd chair, beginning with the third. Inspector B checks every 5th chair, beginning with the fifth. If 98 chairs came down the ramp while both inspectors were working, how many of these chairs were not checked by either of these two inspectors?</p>
<p>answer is 53</p>
<p>Please explain how to do this in a quick manner. Thanks!!!</p>
<p>divide 98 by 3, which is 32 and 98 by 5 which is 19.
total check is 51,
i think the answer is 47, but i don't know, i only got 780 on iic :(</p>
<p>You want to subtract the number of chairs checked from 98; A checks chair numbers that are multiples of 3, chairs 3<em>1 through 3</em>32; B checks chair numbers that are multiples of 5, chairs 5<em>1 through 5</em>19; however A and B can check the same chairs, like chair 30; the chairs they both check are multiples of both 3 and 5, so they're multiples of 15. They both check chairs 15<em>1 through 15</em>6. So the number of chairs checked is 32+19-6=45. 98-45=53. :)</p>
<p>uh.. the first post was kinda right... i think its 98/3 and 98/5 which is 32 and 19. for the multiples of each number. soo when u add them its 32+19= 51.. then you add 2 cuz those chairs were not checked cuz.. the first guy check them starting with the third one. the second guy started with the 5th chair. that is my conclusion. so 51+2 = 53</p>