Question

Two groups of student, whose average ages are 20 years & 30 years, combine to form third
group whose average age is 23 years. What is the ratio of the no. of students in the first group to the number of students in the second group?​

Answer 1

Answer:

5

Step-by-step explanation:

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Answer 2

The ratio of the no. of students in the first group to the number of students in the second group is  7 : 3.

Given: Two groups of students, whose average ages are 20 years & 30 years, combine to form a third group whose average age is 23 years.

To Find: The ratio of the no. of students in the first group to the number of students in the second group.

Solution:

Let the number of students in the first group of 20 years be 'x'

Let the number of students in the second group of 30 years be 'y'

So, the total age in the first group is = 20x

and total age in the second group is = 30y

It is said that the third group is a combination of the previous two groups.

So, the total number of students in third group = x + y

The average age of the third group is = 23

So, the total age of the third group = 23 ( x + y )

Framing an equation from the given problem statement, we get;

      20x + 30y = 23 ( x + y )

 ⇒  30y - 23y = 23x - 20x

 ⇒  7y  =  3x

 ⇒   x/y = 7/3

 ⇒   x : y = 7 : 3

Hence, the ratio of the no. of students in the first group to the number of students in the second group is  7 : 3.

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