In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: what least no . must be subtracted from 50248 so that remaining no . is divisible by 20 ? 
Options: a ) 3 , b ) 2 , c ) 4 , d ) 8 , e ) 6
[EX A]: d

[EX Q]: Problem: what is the minimum percentage increase in the mean of set f { - 4 , - 1 , 0 , 6 , 9 } if its two smallest elements are replaced with two different primes ? 
Options: a ) 25 % , b ) 50 % , c ) 75 % , d ) 100 % , e ) 200 %
[EX A]: d

[EX Q]: Problem: a box contains either blue or red flags . the total number of flags in the box is an even number . a group of children are asked to pick up two flags each . if all the flags are used up in the process such that 60 % of the children have blue flags , and 60 % have red flags , what percentage of children have flags of both the colors ? 
Options: a ) 5 % , b ) 10 % , c ) 15 % , d ) 20 % , e ) it can not be determined
[EX A]:
d