Question

The mean marks of 10 boys in a class is 70%, whereas the mean marks of 15 girls is 60%. the mean marks of all the 25 students is

Answer 1

Answer:

$Mean \: marks \: of \: 25\:students= 64\%$

Step-by-step explanation:

Number of students in the class = 25

Mean marks of 10 boys = 70%

$\boxed {Mean = \frac{sum\: of \: the \: observations }{Number\:of \: observations }}$

$Mean\: marks \: of \: boys = 70\%$

$\implies \frac{sum \: of \: the \: marks }{10}=70\%$

$\implies sum \: of \: marks \: 10 \:boys = 700\%$

$Mean\: marks \: of \: 15\:girls = 60\%$

$\implies sum \: of \: marks \: 15 \:boys = 15\times 60\%\\=900\%$

$Mean \: marks \: of \: 25\:students =\frac{700+900}{25}\\=\frac{1600}{25}\\=64\%$

Therefore,

$Mean \: marks \: of \: 25\:students= 64\%$

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Answer 2

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{lgathered}\implies sum \: of \: marks \: 15 \:boys = 15\times 60\%\\=900\%\end{lgathered}

⟹sumofmarks15boys=15×60%

=900%

\begin{lgathered}Mean \: marks \: of \: 25\:students =\frac{700+900}{25}\\=\frac{1600}{25}\\=64\%\end{lgathered}

Meanmarksof25students=

25

700+900

=

25

1600

=64%

So 25 student = 1600=64%