Question

average of the student of a class is 12 years the average age of 15 of them is 10 years and the average age of the remaining is 13 year how many students are there in a class

Answer 1

Answer:

There are 45 students in the class.

Step-by-step explanation:

Let the total number of students in the class be "x",

We know( formula ),

Average = ( sum of quantities ) / ( number of quantities )

According to the question, average age of students of the class is 12 years,

So,

= >  12 years = ( sum of ages of all students in years ) / x

= >  12 x = sum of ages of all students

Also, average age of 15 of them is 10 years,

= >  10 = ( sum of ages of 15 students ) / 15

= >  150 = sum of ages of 15 students

Average age of remaining students  is 13 years,

= >  13 = ( sum of ages of all students - 150 ) / ( x - 15 )

= >  13( x - 15 ) = ( 12x - 150 )

= >  13x - 195 = 12x - 150

= >  13x - 12x = 195 - 150

= >  x = 45

Therefore the total number of students in the class is 45.

Answer 2

Answer:

45 is the correct answer

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