Out of 300 student in final year in senior secondary school, 200 are offering biology and the150 offering chemistry how many are offering neither biology nor chemistry

Answer 1

Universal set = 300
Biol only = 200 - x
Chem only = 150 - x
Biol nd chem = x
Biol nd chem = 200 - x + x + 150 - x = 300
Biol nd chem = - x + 350 = 300
Collect like terms
Biol nd chem = 350 - 300 = x
X = 50
(Chem U biol)' = chem only + physics only + chem nd physics - universal set
(chem U biol)' = 150 + 50 + 100 - 300
(chem U biol)' = 0
Therefore 0 people are offering neither biology nor chemistry