Latest Infosys Aptitude Question SOLUTION: today question date 16 sep 2016 1 if A and B work together , they will complete a job in 7.5days.however, if A works alone and completes half of the work and then B takes over an

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today question date 16 sep 2016

1 if A and B work together , they will complete a job in 7.5days.however,
if A works alone and completes half of the work and then B takes over and
complete the remaining half alone, they will take 20days
.how long will B alone takes to do the work if A is more efficient than B?

ans 30

2 .In how many different ways can 5 girls and 5 boys form a circle such that the boys and the girls alternate?

Options
1) 2880
2) 1400
3) 1200
4) 32

Asked In Infosys RABIRANJAN KUMAR SINGH (7 years ago)

Unsolved Read Solution (8)

Is this Puzzle helpful?   (45)   (12) Submit Your Solution Time and Work

Read Solution (8) :

sreehitha konidala  (7 years ago)

five girls can be seated in circle in (5-1)! ways=4!=24
remaining boys can be placed in 5! ways=120
total ways =120*24=2880

Is this solution Helpfull? Yes (16) | No   

Gaurav Ravindra Shete  (7 years ago)

2) After fixing one girl, the remaining 4 girls can sit in 4! Ways.
Since boys and girls have to alternate, there will be 5 places, one place each for boys in between the girls. These 5 places can be filled by 5 boys in 5! Ways.
So, the required no.of ways = 5!*4!
= 5*4*3*2*1*4*3*2*1
= 2880 ways

Is this solution Helpfull? Yes (15) | No (1)  

Devendra Marghade  (7 years ago)

10 days

(1/A)+(1/B)= 2/15 ----(i) and (1/2)/(1/A) + (1/2)/(1/B) = 20 ----(ii)
From (ii), (A/2) + (B/2)= 20 or A+B=40
As we require B, substitute A=40-B in (i), we have 1/(40-B) + (1/B)= 2/15
=> B^2 -40B +300=0
=> (B-10)(B-30)=0 , B= 30 or 10
As A+B=40 and A is more efficient than B, so A=30 and B=10

Is this solution Helpfull? Yes (10) | No (8)  

sushant kumar  (7 years ago)

5 girls can be arranged in a circle as = 4!
remaining 5 boys can be arranged at 5 places (one place between any two consecutive girls)= 5!
combining both final answer= 4! * 5! = 2880

Is this solution Helpfull? Yes (2) | No   

Nirujogi varaprasad  (7 years ago)

5!*5!=1400

Is this solution Helpfull? Yes | No (23)  

shamlik husan bano anees  (7 years ago)

5!*4!=2880

Is this solution Helpfull? Yes | No   

swarnalatha  (6 years ago)

5!*4!
2880

Is this solution Helpfull? Yes | No   

tejasri  (5 years ago)

After fixing one girl, the remaining 4 girls can sit in 4! Ways.
Since boys and girls have to alternate, there will be 5 places, one place each for boys in between the girls. These 5 places can be filled by 5 boys in 5! Ways.
So, the required no.of ways = 5!*4!
= 5*4*3*2*1*4*3*2*1
= 2880 ways

Is this solution Helpfull? Yes | No   

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