For an examination consisting of three subjects-Maths, Physics and Chemistry, 280 students appeared. When the results were declared, 185 students had passed in Maths, 210 had passed in Physics and 222 had passed in Chemistry.
All those except 5 students who passed in Maths, passed in Physics.
All those except 10 students who passed in Maths, passed in Chemistry.
47 students failed in all the three subjects.
200 students who passed in Physics also passed in Chemistry.
A student has to pass in at least two subjects to get promoted. How many students get promoted ?
Correct Answer: (2) 23
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
Required answer
= x + y + z + w
= 9 + 29 + 4 + 171 = 213