IBPS RRB Office Assistant 2020 Paper

Sol. (Q. Nos. 51-55) According to the question,
Number of students = 280
Students who cleared Maths = 185
Students who cleared Physics = 210
Students who 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)
On adding Eqs. (iv), (v) and (vi) and then subtracting Eq. (vii), we get
x + y + z + 2w = 384 ...(viii)
On adding Eqs. (i), (ii) and (iii),
x + y + z + 3w = 555 ... (ix)
On subtracting Eq. (viii) from Eq. (ix), we get
w = 171
From Eq. (i), x = 9
From Eq. (ii), z = 200-171 = 29
From Eq. (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 passed in Chemistry only = 18