a = 28 (car pools) (red)
b = 31 (took buses) (orange)
c = 42 (drove to school) (yellow)
d = 9 (car pools and buses) (a meets b)
e = 10(used car pools and sometimes their own cars) (a meets c)
f = 6 (used buses as well as their own cars) (b meets c)
g = 4 (used all three methods) (all 3 meet)
*Remember all d,e,f involves region g
rest all calculations are simple
1.How many students use none of the three methods?
u-(a+b+c-d-e-f+g) = 100-((28+31+42)-9-10-6+4) = 20
2.How many students use car pools exclusively to get to school?
a-(d+e-g) = 28-(9+10-4) = 13 g \\ as g is repeated twice so we subtract g\\
3.How many students use buses exclusively to get to school?
b-(d+f-g) = 31-(9+6-4) = 20 \\ as g is repeated twice so we subtract g\\
3 comments:
I don't understand this part...
u-(a+b+c-d-e-f+g) = (100-(28+31+42)-9-10-6+4) = 20
Why is it (28+31+42) then -9-10-6+4? I mean, why you +4 at the end? Shouldn't all the signs be minus? o.o?
This part...
a-(d+g+e) = 28-(9+10-4) = 13
Why you get (9+10-4)? Shouldn't it be 28-(9+10+4)...?
This part also...
b-(d+g+f) = 31-(9+6-4) = 20
I don't understand why the sign at the end is negative... that is, -4...
Sorry if I sounded stupid... But I found it hard to cope with this kind of question, please help, thanks =D
P/S: Can be my tutor for this chapter on drawing and solving of venn diagrams? ^^
I have edited the solution once again go through it...if u have any problem plz...tell
Now if u don't understand take a notebook and a pencil start colouring the region as used except u .you will notice repeatation of g part is either one more time or less.
Just do it even then it is not clear just let me know
I have no problem being ur tutor but I am having very limited time...
let me know if u have any problem
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