The average age of 20 boys in a class is 12 years. 5 new boys are admi...
Given:
- The average age of 20 boys in a class is 12 years.
- 5 new boys are admitted to the class whose average age is 7 years.
To find: The average age of all the boys in the class.
Solution:
Let's first find the sum of ages of 20 boys in the class using the formula:
Sum of ages of 20 boys = 20 × 12 = 240
Now, let's find the sum of ages of the 5 new boys using the formula:
Sum of ages of 5 new boys = 5 × 7 = 35
The total number of boys in the class after the admission of new boys = 20 + 5 = 25
The sum of ages of all 25 boys in the class = Sum of ages of 20 old boys + Sum of ages of 5 new boys
= 240 + 35
= 275
The average age of all the boys in the class = Sum of ages of all boys / Total number of boys
= 275 / 25
= 11
Therefore, the average age of all the boys in the class is 11 years. Hence, option (a) is the correct answer.
The average age of 20 boys in a class is 12 years. 5 new boys are admi...
Given:
- Average age of 20 boys = 12 years
- 5 new boys with an average age of 7 years are added to the class
To find:
- New average age of all boys in the class
Solution:
Step 1: Find the sum of ages of the 20 boys
- Sum of ages of 20 boys = 20 x 12 = 240
Step 2: Find the sum of ages of the 5 new boys
- Sum of ages of 5 new boys = 5 x 7 = 35
Step 3: Find the total sum of ages of all 25 boys
- Total sum of ages of all 25 boys = 240 + 35 = 275
Step 4: Find the new average age of all 25 boys
- New average age of all 25 boys = Total sum of ages of all 25 boys / Total number of boys
- New average age of all 25 boys = 275 / 25 = 11
Therefore, the new average age of all the boys in the class is 11 years.
Hence, option A is the correct answer.