A group of 2193 students were surveyed about the courses they were taking at
their college with the following results:
1192 students said they were taking Dance.
1143 students said they were taking English.
1199 students said they were taking Math.
583 students said they were taking Dance and English.
697 students said they were taking English and Math.
646 students said they were taking Dance and Math.
372 students said they were taking all three courses.
Venn diagram clues are nearly always give in the reverse order
from the order in which you use them, so we take them in the
reverse order and begin with the last clue and end with the first
clue:
372 students said they were taking all three courses.
So V=372. We fill that in:
646 students said they were taking Dance and Math.
So IV+V=646, so substituting V=372, IV=274. We fill that in:
697 students said they were taking English and Math.
So V+VI=646, so substituting V=372, VI=325. Fill that in:
583 students said they were taking Dance and English.
So II+V=583, so substituting V=372, we get II=211. We fill that in:
1199 students said they were taking Math.
So IV+V+VI+VII=n(M)=1199 and substituting for IV,V and VI gives VII=228.
We fill that in:
1143 students said they were taking English.
So II+III+V+VI=n(E)=1199 and substituting for II,V and VI gives III=235.
We fill that in:
1192 students said they were taking Dance.
So I+II+IV+V=n(D)=1199 and substituting for II,IV and V gives I=335.
So fill that in:
A group of 2193 students were surveyed about the courses they were taking....
So I+II+III+IV+V+VI+VII+VIII=n(U)=n(universal set)=2193, and substituting for
I,II,III,IV,V,VI and VII gives VIII=213. So fill that in (the number who
took none of the courses):
a) How many students took Dance or Math, but not English?
They were I,IV and VII, or 335+274+228=837
b) How many students took Dance, English, or Math?
That's all 2193 except those 213 in VIII who took none of the courses.
2193-VIII = 2193-213 = 1980
c) How many students took Dance & English or took English & Math?
Those that took Dance & English were II+V = 211+372
Those that took English & Math were V+VI = 372+325
But WE MUST BE CAREFUL HERE!!! If we added all those together we
would be counting the 372 TWICE! So we must add it only once, so the
answer here is II+V+VI = 211+372+325 = 908
d) How many students took English and Math, but not Dance?
That's VI, which is 325
e) How many students took Dance or didn't take English?
Those that took Dance were given as 1192 which was I+II+IV+V
Those that didn't take English were I+IV+VII+VIII.
But AGAIN WE MUST BE CAREFUL HERE!!! If we added all those together we
would be counting the I and IV TWICE! So we must add those only once, so the
answer here is I+II+IV+V+VII+VIII = 335+211+274+372+228+213 = 1633
f) How many students took none of the courses?
We've already answered that. It's VIII or 213.
Edwin