JAMB - Mathematics (2002 - No. 2)
In a school, 220 students offer Biology or Mathematics or both. 125 offer Biology and 110 mathematics. How many offer Biology but not Mathematics?
95
80
125
110
설명
Hint: Represent the question in a venn diagram, such that
n(B ∩ M) = x
n(B) only = 125-x
n(M) only = 110-x
=> 125-x + 110-x + x = 220
=> x = 15.
n(B) only = 125 - 15 = 110
n(B ∩ M) = x
n(B) only = 125-x
n(M) only = 110-x
=> 125-x + 110-x + x = 220
=> x = 15.
n(B) only = 125 - 15 = 110