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Help!!

AqsaMx

Don't understand how to do these type questions, can anyone help??

(edited 7 years ago)

Reply 1

Bananapeeler

Sure, it's about looking at things logically and seeing what information you have available. So there are 106 people total, but if we add up each category the total is 126. In other words, some people fall into more than one category and so have been counted more than once. basically, there are 20 "extras" that are a result of people either being in two or three categories. Q18 tells us that there are three people in three categories, so they account for 9 rather than 3.
Now there are probably other ways to go about solving it, but algebraically:
Let N=the number of people in one category
Let X=the number of people in two categories
N+2X+9=126
X's count for two, three people counted thrice = 9, all good?

we also have N+X+3=106 since they must add up to the number of participants

If we minus the top from the bottom we get: X+6=20 and X=14
So N=89

However, having spent 10 minutes doing this I just realised some people could be in none of the categories, i.e. born abroad, under 1.6m and right handed so the answer should be E....

(edited 7 years ago)

Reply 2

RDKGames

Study Forum Helper

Original post by AqsaMx

Don't understand how to do these type questions, can anyone help??

18. There are 106 people, and 126 traits that spread across this sample. We are told 3 of them possess all 3 traits, so this takes up 3 people and 9 traits. Let's narrow down the sample as we dont want people with all 3 traits. 106-3=103 people and 126-9=117. Now we have 117 traits spread over 103 people. If we are to assign 1 trait per person we would have 14 traits left over, which means 14 people can fit in 1 more trait, hence them having 2 traits. Now we know that 14 people have 2 traits. So we can subtract those people from our current sample and get the amount of people having only one trait; 103-14=89 hence 89 people only have 1 trait.

19. No way to tell because we are not told the links between the traits, ie we don't know how many of the 50 tall people are left handed, etc...

20. Now we focus on the amount of people who are left-handed. There are 14 of them in total. We are told 3 of them have all 3 traits so we can subtract them from the total, hence giving us 11 people who are left handed only or possessing two traits. Next we are told there are 2 people who are left-handed + taller than 1.6m, so we can subtract those 2 from 11 and get 9 people remaining. Continuing on, there are twice as many people who are just left handed than those who are left handed + born in England. As we have taken care of the previous information, we can say that there are

x

amount of people who are left handed + born in England therefore there are

2x

amount of people who are just left handed. If we sum these people up, we get that

9=x+2x

which gives us

x=3

. From here we can conclude that there are only 6 people who are only left handed from the fact that there are

2x=2(3)=6

of them!

These questions are all about following through the information and considering all the possibilities carefully, you may use equations as shown in the post above if you wish to make things look neater as well, whichever way helps! :smile:

(edited 7 years ago)

Reply 3

RDKGames

Study Forum Helper

Original post by Bananapeeler

However, having spent 10 minutes doing this I just realised some people could be in none of the categories, i.e. born abroad, under 1.6m and right handed so the answer should be E....

I agree, I think they worded the question wrong by not stating the fact that every single person in that sample has at least one of those traits. Feels wrong to just assume that they do but oh well :h:

Reply 4

AqsaMx

Thank you so much for taking so much time to explain!!
With Q18) I don't get how we assume that 126 people represent 126 traits??

Reply 5

RDKGames

Study Forum Helper

Original post by AqsaMx

Thank you so much for taking so much time to explain!!
With Q18) I don't get how we assume that 126 people represent 126 traits??

No problem! :h:

We are told there are 106 people in the context, and in order to get the 126 traits, we simply add the amounts of them that we are told (62+50+14=126) which means that's the amount of traits that spread over the 106 people.