GRE Quant Ep 17: Overlapping Sets

[@VigilVanDijk666]

Absolutely amazing collection of questions. I am yet to see anyone addressing such variations in these type of questions. Great going!

[@GRENinjaTutoring]

Thank you so much!

[@elliekiss77]

Great explanation ! Thank you😊

[@GRENinjaTutoring]

Thank you so much!

[@SHAKIL-p2y]

Thank you sir specially for the second half .

[@GRENinjaTutoring]

Thank you for watching and taking the time to write this! Have a wonderful time studying, and please let us know how things go for you.

[@quantabot1165]

Just an alternative way of thinking for riding and cycling question. We can immediately see that 84-12 = 72 people don't row(they do cycling instead) , and 150-48= 102 people in total don't row(they do other sports). Now remove the 72 who do cycling from this and there we have it, 30 people who neither row nor do they cycle

[@ramachandrarao6469]

Very helpful. Thanks

[@GRENinjaTutoring]

Thank you so much!

[@martynadydyk9714]

Q4: Can we not just determine that beer = 2xwine so 350 total of beer and substract this 381-350= 31 ?

[@samarhello]

Alternate, logic based method for Q3: You notice that the number of people that did cycling or rowing is 84+48=132. From the information given, of these 132 'counts', 12 of them are accounted for by people who did both cycling AND rowing, i.e. who are being double counted. By subtracting 12 from 132, you are effectively disregarding the overcount and calculating the number of people who did cycling OR rowing to be 120. Of course, the number of people who did NEITHER cycling nor rowing would just be the total number of people minus the people who did EITHER cycling OR rowing, i.e. 150-120=30.

[@sophiecampos4860]

for question 5, would it be easier to solve for 300 by 75x4 instead of finding the least common multiple? Or did 75x4 happen to equal 300 and this shortcut wont work for other problems?

[@GRENinjaTutoring]

In this case, you're totally right that it would have been easier to just do 75*4 to get to 300. However, it won't be the case in every scenario. For example, if we were looking at 6 and 8 (instead of 75 and 4) then multiplying them together would give 48 but the LCM of 6 and 8 is 24. This means that we might think we're looking for a multiple of 48 when we're really looking for a multiple of 24. We'd think the list of numbers we're looking for was 48, 96, 144, 192... when the actual list we'd be looking for was 24, 48, 72, 96, 120, 144, 168, 192... and we'd miss a few potential correct answers. We can't assume that the LCM of any two numbers is given by multiplying them together. If we default to finding the LCM in the way shown in the video, it might take us a bit longer but it will probably mean we make fewer errors. I hope that helps!

[@priscillaziegler4154]

For Q3 can't it be done easily algebraically also? If we know the total that do both (132) we can subtract the overlap (120) from that and then subtract that from the overall total (150-120) to get 30? Same for q 1

[@GRENinjaTutoring]

Yes, you can use algebra to solve these questions. Thank you for adding your method here! It's great to see different ways of answering these questions listed. There are often several methods you could use to solve a GRE question, but one of the challenges of the test is choosing the right one. For overlapping sets questions, we suggest using this grid method because it will cover the greatest number of questions with the same method. I hope that helps!

[@hita1704]

could you tell me the formula for solving these questions please?