Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    3
    ReputationRep:
    Name:  image.jpg
Views: 67
Size:  297.2 KBName:  image.jpeg
Views: 68
Size:  117.0 KBName:  image.jpeg
Views: 68
Size:  117.0 KBDon't understand how to do these type questions, can anyone help??
    Offline

    10
    ReputationRep:
    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....
    • Community Assistant
    • Welcome Squad
    Online

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    (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!
    • Community Assistant
    • Welcome Squad
    Online

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    (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
    • Thread Starter
    Offline

    3
    ReputationRep:
    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??
    • Community Assistant
    • Welcome Squad
    Online

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    (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!

    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.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.