Working 5 hours a day, A can Complete a work in 8 days and working 6 hours a day, B can complete the same work in 10 days. Working 8 hours a day, they can jointly complete the work in:
A. 3 days
B. 4 days
C. 4.5 days
D. 5.4 days
Answer: Option A
Solution(By Examveda Team)
1st Method: Working 5 hours a day, A can complete the work in 8 days i.e. = 5 × 8 = 40 hours Working 6 hours a day, B can complete the work in 10 days i.e. = 6 × 10 = 60 hours (A + B)'s 1 hour's work, $$\eqalign{ & = \frac{1}{{40}} + \frac{1}{{60}} \cr & = \frac{{3 + 2}}{{120}} \cr & = \frac{5}{{120}} \cr & = \frac{1}{{24}} \cr} $$ Hence, A and B can complete the work in 24 hours i.e. they require 3 days to complete the work. 2nd Method: % 1 hour's work of A = $$\frac{{100}}{{40}}$$ = 2.5% % 1 hour's work of B = $$\frac{{100}}{{60}}$$ = 1.66% (A + B) one hour's % work, = (2.5 + 1.66) = 4.16% Time to complete the work, = $$\frac{{100}}{{4.16}}$$ = 24 hours Then, $$\frac{{24}}{8}$$ = 3 days They need 3 days, working 8 hours a day to complete the work.Join The Discussion
Comments ( 1 )
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