Solution:Number of students = 280
Cleared Maths = 185
Cleared Physics= 210
Cleared Chemistry = 222
Students who passed in Maths
and Physics = 180
Students who passed in Maths
and Chemistry = 175
Students who passed in Physics and Chemistry = 200
Number of students who
passed in atleast one subject
= 280 - 47 = 233
x + w = 180 ....(i)
w + z = 200 ....(ii)
w + y = 175 ....(iii)
M + x + w + y = 185 ....(iv)
P + x + w + z = 210 ....(v)
C + y + w + z = 222 ....(vi)
M + P + C + y + x + z + w = 233
....(vii)
By (iv) + (v) + (vi) - (vii),
x + y + z + 2w = 384 ....(viii)
by (i) + (ii) + (iii),
x + y + z + 3w = 555 ....(ix)
By (ix) - (viii),
w = 171
From equation (i),
x=9
From equation (ii),
z = 200 - 171 = 29
From equation (iii),
y = 175 - 171 = 4
M = 185 - 4 - 9 - 171 = 1
P = 210 - 9 - 171 - 29 = 1
C = 222 - 4 - 29 - 171 = 18
Number of students who
have passed in all three subjects = 171