In a class, there are 24 boys whose ages is decreased by 4 months, when one boy aged 20 years is replaced by a new boy. Find the age of the new boy. Pick one: A) 9 YEARS B) 10 YEARS C) 12 YEARS D) 14 YEARS E) 15 YEARS
Let age of the new boy was X.   Age decreased = 4 months = 4/12 = 1/3 years   Now, we have formula for this type of questions,   Number of members in the Group * age decreased = difference in ages of boy in and boy out.   24 * (1/3) = 20 -X   X = 12 years.   ANSWER : OPTION 12 YEARS
<result>C</result>
In a class, there are 24 boys whose ages is decreased by 4 months, when one boy aged 20 years is replaced by a new boy. Find the age of the new boy.