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'.

Problem: the average age of 7 men increases by 4 years when two women are included in place of two men of ages 26 and 30 years . find the average age of the women ? 
Options: a ) 42 , b ) 40 , c ) 30 , d ) 18 , e ) 11
a

Problem: in a group of ducks and cows , the total number of legs are 8 more than twice the no . of heads . find the total no . of buffaloes . 
Options: a ) 5 , b ) 4 , c ) 6 , d ) 3 , e ) 2
b

Problem: the arithmetic mean and standard deviation of a certain normal distribution are 17.5 and 2.5 , respectively . what value is exactly 2 standard deviations less than the mean ? 
Options: a ) 10.5 , b ) 11 , c ) 11.5 , d ) 12 , e ) 12.5

e