In
a certain school, 190 students take either Chemistry or physics. 130 take chemistry
and 100 take both subjects. Find those who take physics only.
Solution
In
most cases, OR stands for union whereas AND/BOTH, stands for intersection.
Let
Chemistry = n(C), physics = n(P).
n(C)=
130 ,
n(P)=
?
n(CuP)
= 190,
n(CnP)=
100
Solution
n(CuP)
= n(C) + n(P) - n(CnP)
190
= 130 + n(P) – 100
190
= n(P) + 30
190
- 30 = n(P)
n(P)=
160
physics
only = n(P) – n(CnP)
= 160 – 100
= 60
Hence
those taking only physics are 60.
TRY
THIS………..
In
a certain school, 193 students take either Chemistry or physics. 125 take
chemistry and 90 take both subjects. Find those who take physics only.
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