Question

१)एका शाळेत 600 विद्यार्थी आहेत. त्यातील मुलांचे सरासरी वय 12 व मुलींचे सरासरी वय 11 आहे. शाळेतील सर्वविद्यार्थ्यांचे सरासरी वय 11 वर्षे 9 महिने आहे तर शाळेतील मुले व मुली किती ?​

Answer 1

Given:

In a school of 600 students, the average age of boys is 12 years and that of the girls is 11 years.

If the average age of all the students of the school is 11 years 9 months

To find:

The number of girls and boys in the school

Solution:

Let's assume

"x" → represents the no. of boys in the school

"(600 - x)" → represents the no. of girls in the school

We know,

$\boxed{\bold{Average = \frac{Sum \:of \:terms}{No. \:of\: terms} }}$

So,

The total age of boys = 12x

and

The total age of girls = 11(600 - x)

The average age of all students in the school = $11\frac{9}{12} \:years = \frac{141}{12}= \frac{47}{4}\:years$

∴ The total age of all students = $600 \times \frac{47}{4} = 150 \times 47 = 7050$

Therefore, we can form an equation as:

$12x\: +\: 11(600 - x) = 7050$

$\implies 12x\: +\: 6600 - 11x = 7050$

$\implies 12x - 11x = 7050 - 6600$

$\implies \bold{x = 450}$ ← no. of boys

∴ No. of girls = 600 - x = 600 - 450 = 150

Thus, in the school,

$\boxed{\bold{No.\:of\:boys\:is\:\underline{450}}}.\\\\\boxed{\bold{No.\:of\:girls\:is\:\underline{150}}}.$

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Answer 2

Answer:

Step-by-step explanation: