Average

Step 1: Let the number of boys be $x$ and the number of girls be $y$ .
The total number of people in the group is $x%20%2B%20y$ , and the average age of the group is 18 years. Thus, the total age is: $20x%20%2B%2015y%20%3D%2018(x%20%2B%20y)$ Expanding both sides: $20x%20%2B%2015y%20%3D%2018x%20%2B%2018y$ Simplifying: $2x%20%3D%203y%20%5Cimplies%20x%20%3D%20%5Cfrac%7B3%7D%7B2%7Dy$

Step 2: Find the percentage of boys.
Since $x%20%3D%20%5Cfrac%7B3%7D%7B2%7Dy$ , the total number of boys is $%5Cfrac%7B3%7D%7B2%7Dy$ , and the total number of people is $x%20%2B%20y%20%3D%20%5Cfrac%7B3%7D%7B2%7Dy%20%2B%20y%20%3D%20%5Cfrac%7B5%7D%7B2%7Dy$ . Thus, the percentage of boys is: $%5Ctext%7BPercentage%20of%20boys%7D%20%3D%20%5Cfrac%7Bx%7D%7Bx%20%2B%20y%7D%20%5Ctimes%20100%20%3D%20%5Cfrac%7B%5Cfrac%7B3%7D%7B2%7Dy%7D%7B%5Cfrac%7B5%7D%7B2%7Dy%7D%20%5Ctimes%20100%20%3D%20%5Cfrac%7B3%7D%7B5%7D%20%5Ctimes%20100%20%3D%2060%25$

Final Answer: $%5Cboxed%7B60%25%7D$

High-Yield Trend

Chapter Questions
1 MCQs

Official Solution

Average

High-Yield Trend

Chapter Questions 1 MCQs

Official Solution

Chapter Questions
1 MCQs