Psc Cracker

If A can do a piece of work in ` n ' days,then A's 1 day work is 1/n If M1 persons can do W1 work in D1 days for T1 hours and M2 persons can do W2 work in D2 days for T2 hours then M1 D1 T1 W2 = M2 D2 T2 W1 If A can finish a work in `x' days and B can finish the same work in `y' days, then time taken by both to finish the work is xy / (x+y) days. [Here 1 day work A=1/x , B=1/y . So 1 day both A+B work= 1/x + 1/y =(x +y) /xy . Number of days = xy / (x+y) ] If A and B together can do a piece of work in x days and A alone can do it in y days then B alone can do it in xy/ (y-x) days If A, B and C can do a work in x,y, and z days respectively, then all of them working together can finish the work in xyz / (xy +yz + xz) days Questions 1.If 18 members can complete a work in 12 days. How may more members are needed to complete this work in 9 days? ( Fireman Driver NCA 2020 ) M1 D1=M2 D2 18 x 12= M2 x 9 M2=18*12/9 = 24 More ...