Question

The average age in a city of 10,000 is 40 years the average of half of them is 15 years the average of remaining ones is ?

Answer 1

Step-by-step explanation:

Sum of ages of 10000 ppl = 10000 × 40 = 400000

Half of 10000 ppl = 5000 ppl.

Sum of 5000 people = 5000 × 15 = 75000

So,

sum of remaining ones = 400000 - 75000 = 325000.

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Answer 2

Answer:

The average age of the entire city population is represented by X.

The number of people in the city is represented by n.

The average age of the first half of population is represented by Y.

The number of people in first half of population is represented by n1.

Equation 1: X = (n1*Y + (n-n1) * Z) /n

Where Z is the average age of the remaining population.

Given:

X = 40 (average age of the entire city population)

n = 10,000 (number of people in the city)

Y = 50 (average age of the first half of population)

n1 = 5,000 (number of people in first half of population)

We can substitute the values in equation 1 to get the average age of remaining population:

Z = (nX - n1Y) / (n-n1)

Z = (10,000*40 - 5,000*50) / (10,000-5,000)

Z = (400,000 - 250,000) / 5,000

Z = 150,000 / 5,000

Z = 30

Therefore, the average age of the remaining population is 30