One woman and one man can build a wall together in four hours, but the woman would need the help of two girls in order to complete the same job in the same amount of time. If one man and one girl worked together, it would take them eight hours to build the wall. Assuming that rates for men, women and girls remain constant, how many hours would it take one woman, one man, and one girl, working together, to build the wall?  Answers.
A) 5/7	B) 1	C) 10/7	D) 12/7	E) 24/7
Solution:Let work done by man, women and girl per hour be m,w,g respectively.   Then, m+w = 1/4--&gt;(1) , w + 2g = 1/4--&gt;(2) and m + g =1/8--&gt;(3).   No. of hours it would take forone woman, one man, and one girl, working together, to build the wall,n = 1/m+w+g   From (1) and (2), m=2g and from (3) g=1/24,m=1/12 and w=1/6.   So, n = 1/(7/24) = 24/7   Option, 24/7
<result>E</result>
One woman and one man can build a wall together in four hours, but the woman would need the help of two girls in order to complete the same job in the same amount of time. If one man and one girl worked together, it would take them eight hours to build the wall. Assuming that rates for men, women and girls remain constant, how many hours would it take one woman, one man, and one girl, working together, to build the wall?