Problema Solution
a woman can do a certain job in 10 hours and her daughter can do it in 12 hours. after the woman and her daughter have been working for 1 hour , they are joined by the mother and the three complete the job in 3 more hours. how long will it take the mother to do the job by herself?
Answer provided by our tutors
Rate of women work done= (1/10)*100= 10% of work per hour.
Rate of daughter work done=(1/12)*100=8.33 % of work per hour.
So, work done in one hour by woman and daughter= 10+8.33=18.33 % of work
Let rate of work done by mother= x %.
So, 3(18.33)+3x=100-18.33
55+3x=81.67
3x=81.67-55=26.67
x=26.67/3=8.89 %
Time taken by mother to complete job by itself= 100/8.89=11.24 hours.