The mean marks of 10 boys in a class is 70% where as the mean marks of 15 girls is 60%. The mean marks of all the 25 students is ?
Select one:
a. 52%
b. 60%
c. 64%
d. 55%
Answers
Answer:
Meanmarksof25students=64%
Step-by-step explanation:
Number of students in the class = 25
Mean marks of 10 boys = 70%
\boxed {Mean = \frac{sum\: of \: the \: observations }{Number\:of \: observations }}
Mean=
Numberofobservations
sumoftheobservations
Mean\: marks \: of \: boys = 70\%Meanmarksofboys=70%
\implies \frac{sum \: of \: the \: marks }{10}=70\%⟹
10
sumofthemarks
=70%
\implies sum \: of \: marks \: 10 \:boys = 700\%⟹sumofmarks10boys=700%
Mean\: marks \: of \: 15\:girls = 60\%Meanmarksof15girls=60%
\begin{gathered}\implies sum \: of \: marks \: 15 \:boys = 15\times 60\%\\=900\%\end{gathered}
⟹sumofmarks15boys=15×60%
=900%
\begin{gathered} Mean \: marks \: of \: 25\:students =\frac{700+900}{25}\\=\frac{1600}{25}\\=64\%\end{gathered}
Meanmarksof25students=
25
700+900
=
25
1600
=64%
Therefore,
Mean \: marks \: of \: 25\:students= 64\%Meanmarksof25students=64%