Question

The average age of 20 girls is 25 years. The average age of another 30 girls is K years. If the average age of all 50 girls is 34 years, then what is the value of K
1. 40
2. 35
3. 25
4. 30

Answer 1

Correct Answer - Option 1 : 40

Given:

The average age of 20 girls = 25 years

The average age of 30 girls = k years

The average age of 50 girls = 34 years

Formula used:

Average = Sum of observations/Number of observations

Calculation:

According to the question,

Total age of 50 girls = Average × Number of students

⇒ 34 × 50

⇒ 1700      ----(1)

Similarly, total age of 20 girls = 25 × 20

⇒ 500      ----(2)

Now, total age of 30 girls = k × 30

⇒ 30 × k      ----(3)

From equation (1), (2), and (3), we get

Total age of 50 girls = Total age of 20 girls + Total age of 30 girls

1700 = 500 + 30 × k

⇒ 1200 = 30 × k

⇒ 30 × k = 1200

⇒ k = 40

∴ The required value of k is 40.