3) VENN DIAGRAM
The Venn diagram above shows eight regions defined below:
A Physics only
B Music only
C Geography only
D Physics and geography but not music
E Music and geography but not physics
F Physics and music but not geography
G All three subjects
H None of the subjects
G=0, H=24 (no students took all 3 subjects, and 24 took none of the subjects).
A=6, C=8, B=4 (only one subject).
D+E+F=7 (two subjects).
C+D+E=14 (geography total), D+E=6 and F=1.
B+E+F=9 (music total), so E=9-4-1=4 and D=6-4=2.
1) Total physics=A+D+F=6+2+1=9.
2) Total students=A+B+C+D+E+F+G+H=6+4+8+7+0+24=49.