sh hai
Q1.The average age of boys in a class of 30
is 15 years. If 10 more boys join the
class, the average age of the whole class
is reduced by one year. What is the
average age of new comers?
Answers
Answer:
The total of the ages of the 10 new boys has to balance out those 30 "extra" years from the original 30 boys; that means the average age of the 10 new boys has to be 30/10 = 3 years LESS than the new average. Since the new average is 14, the average age of the 10 new boys is 14-3 = 11.
The total of the ages of the 10 new boys has to balance out those 30 "extra" years from the original 30 boys; that means the average age of the 10 new boys has to be 30/10 = 3 years LESS than the new average. Since the new average is 14, the average age of the 10 new boys is 14-3 = 11.Step-by-step explanation:
Hope it will help you dear ❤️
Answer:
The total of the ages of the 10 new boys has to balance out those 30 "extra" years from the original 30 boys; that means the average age of the 10 new boys has to be 30/10 = 3 years LESS than the new average. Since the new average is 14, the average age of the 10 new boys is 14-3 = 11.
Step-by-step explanation:
Since "The average age of boys in a class of 30 is 15 years", the sum of their ages is 30*15 = 450 years.
Let N be the average age of 10 newcomers. Then the sum of their ages is 10N.
The total sum of 30 + 10 boys is 450 + 10N, and their average age is .
So, from the condition you have this equation
%28450%2B10N%29%2F40 = (15-1) = 14.
Then 450 + 10N = 14*40 = 560 ====> 10N = 560 - 450 = 110 ====> N = = 11.
Answer. The average age of newcomers is 11 years.
Check. %2830%2A15+%2B+11%2A10%29%2F40 = 14. ! Correct !
Solved.
Or even simpler logical analysis:
Since "The average age of boys in a class of 30 is 15 years", the sum of their ages is 30*15 = 450 years.
After joining 10 newcomers, the average age became 15-1 = 14 years; hence, the sum of ages of all 40 students
of the class is 40*14 = 560 years now.
The difference 560-450 = 110 years IS THE SUM of ages of the 10 newcomers.
Hence, their average age is 110%2F10 = 11 years.
You got the same answer.
Surely, this "logical analysis" is the same solution, simply presented in the wording form.