Question

A class of 30 boys and 15 girls is given a test in Mathematics. The average marks
obtained by boys is 15 and by girls is 6. The average of whole class is​

Answer 1

Answer:

4

Step-by-step explanation:

what is the answer plz.tell me

Answer 2

The average of the whole class is 12.

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Let's understand a few concepts:

To calculate the total marks we will use the following formula for the average:

$\boxed{\bold{Average = \frac{Sum \:of\:observations}{Number\:of\:observations} }}$

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Let's solve the given problem:

Finding total marks obtained by 30 boys:

The number of boys = 30

The average marks obtained by 30 boys = 15

∴ The total marks obtained by 30 boys = $30 \times 15 = 450$

Finding total marks obtained by 15 girls:

The number of girls = 15

The average marks obtained by 15 girls = 6

∴ The total marks obtained by 15 girls = $6 \times 15 = 90$

Finding the average marks of the whole class:

The total number of students (boys + girls) = 30 + 15 = 45

The total marks obtained by boys and girls together = 450 + 90 = 540

Therefore, by using the above formula of average, we get

The average marks of the whole class is,

= $\frac{Total\:marks\:ontained\:by \:45 \:students }{Total\:number\:of\:students}$

= $\frac{540}{45}$

• on dividing both numerator and denominator by 9

= $\frac{60}{5}$

• on dividing both numerator and denominator by 5

= $\bold{12}$

Thus, the average of the whole class is​ 12.

#SPJ3

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