Latest Infosys Aptitude Question SOLUTION: Q5) If A and B can do a piece of work in 7.5 days. If B works 1/2 of work and remaining work was completed by A, taking total time of 20 days to complete the work. If b is more eff

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Q5) If A and B can do a piece of work in 7.5 days. If B works 1/2 of work and remaining work was completed by A, taking total time of 20 days to complete the work. If b is more efficient then B can do work in how many days?

Asked In Infosys Satya Chamana (7 years ago)

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Devendra Marghade  (7 years ago)

10 days

1/A + 1/B = 2/15 or (A+B)/AB= 2/15 ----(i)
(1/2)/(1/A) + (1/2)/(1/B) = 20 or A/2 + B/2 = 20 or A+B= 40 ----(ii)
Substituting A+B= 40 from (ii) in (i), we get AB= 300
Now finding the factors of 300, whose sum is 40, we have 10 and 30
As B is more efficient than A, B can do the work in 10 days.

Is this solution Helpfull? Yes (17) | No (15)  

Deepmoy Banerjee  (7 years ago)

for doing 1/2 work A takes 20 days
for doing 1 work A will take 40 days
sp 1/40+1/B=2/15 which gives B does the work in 10 days and is more efficient as it shows

Is this solution Helpfull? Yes (13) | No (11)  

Rajaboina Radhika  (6 years ago)

a and b oneday work is 1/7.5
half of the work completed by a in 20 days
=> a takes 40 days to complete the work
a+b=1/7.5
b oneday work =1/7.5-1/40
b can complete the work in 9.23 days =10 days

Is this solution Helpfull? Yes (9) | No (1)  

SHAHNAWAZ ALAM  (7 years ago)

10 days
2{(1/x)+(1/(20-x))}=1/7.5

so, x=10,30
as b is more efficient, hence B can do work in 10 days.

Is this solution Helpfull? Yes (4) | No   

himanshu  (6 years ago)

approx 10 days, as A will do whole work in 40 days take lcm of 40 and 15/2
it will come out 120 now A's one day work=120/40=3 and (A+B) one day work =120*2/15=16.
hence B's one day work=16-3=13 so, B will do whole work in 120/13=9.23 Days

Is this solution Helpfull? Yes (2) | No   

ssankar  (6 years ago)

1/a=1/b=1/7.5
1/a+1/b=4/30
since A is more efficient
a can do 3/30and b=1/30
a finishes half work so 1/2 work is left hence 1/2 by b
that is 15 days
B can do the work in 15 days

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