A and B completed a work together in 5 days. had A worked at twice the speed and B at half the speed, it would have taken them four days to complete the job. How much time would it take for A alone to do the work?
A. 10 days
B. 20 days
C. 25 days
D. 15 days
E. 24 days
Answer: Option A
Solution(By Examveda Team)
Assume work to be done 100%. First case, A + B = $$\frac{{100}}{5}$$ = 20% work done per day -------- (1) Second case, 2A + $$\frac{{\text{B}}}{2}$$ = $$\frac{{100}}{4}$$ = 25% work done per day ------ (2) On solving equation (1) and (2), we get A = 10 daysThis Question Belongs to Arithmetic Ability >> Time And Work
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Comments ( 3 )
Related Questions on Time and Work
A. 18 days
B. 24 days
C. 30 days
D. 40 days
let
A can do the work in x days
B can do the work in y days
1st condition
1/x + 1/y =1/5......(1)
[we know, speed= total work/days
2nd condition
2✘1/x + 1/2y = 1/4.......(2)
equation 1✘1/2 - 2✘ 1
we get
x =10
answer A = 10 days
Let, A can do x part/ day
B can do y part/day
So, 5x+5y=1.....(1)
4.2x+4.y/2 =1
Or, 8x+2y=1.....(2)
From, (1)-(2) we get
x=1/10
Now, A can do 1/10 part in 1 day
A can do 1 part in 10 day
Sir how to solve these two equation..plz explain it