Mathematics, 05.10.2020 14:01 001054213

the mean marks for a french test in a class of 30 boys and 20 girls are 60 and 70 respectively. find the mean mark for the whole class.

Answers: 2

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Answers

Answer from: hannahv10

Step-by-step explanation:

Let, the number of boys be x and number of girls be y.

\begin{gathered}\\Mean \: marks \: of \: boys \\ = \frac{Total \: marks \: of \: boys }{Total \: number \: of \: boys} \\ \\ 70 = \frac{Total \: marks \: of \: boys}{ x } \\ \\ Total \: marks \: of \: boys = 70x \: \: (1) \\ Mean \: marks \: of \: boys \\ = \frac{Total \: marks \: of \: girls }{Total \: number \: of \: girls} \\ \\ 73 = \frac{Total \: marks \: of \: girls}{y} \\ \\ Total \: marks \: of \: girls = 73y \: \: (2) \\ Mean \: marks \: of \: entire \: students \\ = \frac{Total \: marks \: of \:students}{Total \: number \: of \: students } \\ \\ Mean \: marks \: of \: entire \: students \\ = \frac{Marks \: of \:boys + Marks \: of \: girls}{ Number \: of \: boys + Number \: of \: girls } \\ \\ from \: eq \: (1) \: and \: (2) \\ \\ 71 = \frac{70x + 73y}{x + y} \\ \\ 71(x + y) = 70x + 73y \\ \\ 71x + 71y = 70x + 73y \\ \\ 71x - 70x = 73y - 71y \\ \\ x = 2y \\ \\ \frac{x}{y} = \frac{2}{1} \\ \\ \frac{Number \: of \: boys}{Number \: of \: girls} = \frac{2}{1} \\ \\\end{gathered}

Meanmarksofboys

Totalnumberofboys

Totalmarksofboys

70=

Totalmarksofboys

Totalmarksofboys=70x(1)

Meanmarksofboys

Totalnumberofgirls

Totalmarksofgirls

73=

Totalmarksofgirls

Totalmarksofgirls=73y(2)

Totalnumberofstudents

Totalmarksofstudents

Numberofboys+Numberofgirls

Marksofboys+Marksofgirls

fromeq(1)and(2)

71=

x+y

70x+73y

71(x+y)=70x+73y

71x+71y=70x+73y

71x−70x=73y−71y

x=2y

Numberofgirls

Numberofboys

Answer from: Quest

There’s not enough information to answer this question? ?

Answer from: Quest

c. 27 units.

step-by-step explanation:

we are told that in circle a, ∠bae ≅ ∠dae.

we can see from our given diagram that in $\delta bea$ and $\delta dea$ ;

$ba=da$ , as these are radii of our given circle.

$ea=ea$

therefore, $\delta bea\cong \delta dea$ by sas congruence postulate.

hence, side be will be equal to side de as corresponding parts of congruent triangles are congruent. so we can set an equation to find the value of x as:

$3x-24=x+10$

$3x-x=24+10$

$2x=34$

$x=\frac{34}{2}$

$x=17$

now let us substitute x=17 in the expression for the length of be.

$\text{length of be}=3x-24$

$\text{length of be}=3\cdot 17-24$

$\text{length of be}=51-24$

$\text{length of be}=27$

therefore, length of be will be 27 units and option c is the correct choice.

In circle a, ∠bae ≅ ∠dae. what is the length of be? 14 units 17 units 27 units 34 units

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the mean marks for a french test in a class of 30 boys and 20 girls are 60 and 70 respectively. find...