Latest TCS Aptitude Question SOLUTION: A can complete a project in 20 days while B can complete same project in 30 days. If A and B start working together and A leaves the work 10 days before completion of project, then

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A can complete a project in 20 days while B can complete same project in 30 days. If A and B start working together and A leaves the work 10 days before completion of project, then in how many days the project will be completed?

Asked In TCS Arpit Tantia (10 years ago)

Solved Saraswathy Read Solution (32)

Is this Puzzle helpful?   (32)   (11) Submit Your Solution Time and Work

Read Solution (32) :

Swarnali Biswas  (10 years ago)

A's 1day work=1/20;
B's 1day work=1/30;
(A+B) 1day work=(1/20+1/30)=1/12;

It is given that A leaves the work 10 days before completion of the project..
Thus,B alone does the remaining job in 10 days.

So,In 10 days ,B can do 1/3 w ..

Thus,(A+B) have worked (1-1/3)=2/3 w..
(A+B)can do 1/12 work in 1 day...

They did 2/3 w in 8 days.

Total days=(8+10) = 18 (Ans)

Is this solution Helpfull? Yes (75) | No (14)  

Saraswathy  (10 years ago)

A's 1 day work=1/20

B's 1 day work=1/30

A+B's 1 day work= 1/20+1/30 = 1/12

so they ll complete d work in 12 days... but A left before 10 days... So both worked together only for days...

A+b's 2 day work= 2*1/12= 1/6

Remaining work=5/6

Remaining work can be done by B in 5/6*30= 25 days

So the project ll be completed in 2+25 = 27 days

Is this solution Helpfull? Yes (54) | No (48)  

Supriya_kamkar  (9 years ago)

A's 1 day work->1/20
B's 1 day work->1/30

let the project be completed in x days

for (x-10) days A & B work together
so,(1/20+1/30)(x-10)=y

wer,y->work completed in x-10 days

for 10 days B works alone if z is the work done by B
z=10(1/30)=1/3

total work=y+z
1=y+1/3
y=2/3

(1/20+1/30)(x-10)=2/3
so,x=18 days is the ans

Is this solution Helpfull? Yes (15) | No   

Kataria Deepak  (10 years ago)

Let's after 10 days B alone takes x days to complete a whole project.
then A's working day = x-10. and
A's 1 days Work = 1/10, B's 1 days Work = 1/30
therefore
A's (x-10) days work + B's x days work = 1 work

so (x-10)/20 + x/30 = 1 work
=> 30x-300+20x=600
50x=900
x = 18 days to complete whole work.............

Is this solution Helpfull? Yes (12) | No (3)  

raviteja  (9 years ago)

27 is wrong.
x-10/20 + x/30 =1
then x=18 is correct.

Is this solution Helpfull? Yes (10) | No (1)  

Ann Theressa  (10 years ago)

ans 27days
Together they can complete the work in
(20*30)/(20+30)=12days
A work for 2 days (12-10 days) and B work for x days
2/20+x/30=1
x=27

Is this solution Helpfull? Yes (6) | No (15)  

Vaka Syam Prasad Reddy  (9 years ago)

A completes the work in 20 days
B completes the work in 30 days

L.C.M of 20 and 30 is 60, hence the total work to be done is 60 units

A's efficiency = 60/20 = 3 units/day
B's efficiency = 60/30 = 2 units/day

Given A left the project before 10 days , that means B has done the project alone in the last 10 days i.e, 10*( 2 units/day ) = 20 units.

Remaining work = 60 - 20 = 40 units

They both completed 40units of work
40units /(3+ 2)units/day=8

Therefore the project is completed in 10+8 = 18 days

Is this solution Helpfull? Yes (6) | No (2)  

archita chaudhuri  (10 years ago)

a can complete in 20 days.
b " " " 30 days.

a+b = 1/20 + 1/30
=1/12

they can finish the work in 12 days.

but a leaves before 10 days.

b worked for 10 days i.e. 1/3 of the work was completed by b.
so they finished (1-1/3) i.e. 2/3 of the work.
so it took 12 x 2/3 = 8 days.
total time = 10+8 =18 days

Is this solution Helpfull? Yes (5) | No (2)  

karthikeyank  (9 years ago)

Ans : 27 days
A one day work is =1/20
b one day works is=1/30
A+B works is =1/20+1/30=>50/600==>1/12

A+B can complete the work in 12 days..
A leaves the work 10 days before
12-10=2--->2*1/12=1/6
Remaining work is 1-1/6=5/6
B complete the project in 30 days=30*5/6=25days
Already they works 2 days so =25+2=27days
B complete the project in 27 days.......

Is this solution Helpfull? Yes (5) | No (6)  

shivani jindal  (9 years ago)

ans is 18

27 is the wrong answer .

Is this solution Helpfull? Yes (4) | No (1)  

Rupavathi  (9 years ago)

x/20+x/30=1
(30(x-10)+20x)/600=1
50x=900
x=18.
answer is 18 days

Is this solution Helpfull? Yes (2) | No (1)  

Manwar Singh Rawar  (10 years ago)

A's 1day work=1/20;
B's 1day work=1/30;
let they finish their work in x days so
x(1/20 + 1/30) - 10(1/20)=1
-> x=18 days

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

priya gupta  (9 years ago)

The rate of A frac{1}{20} job per day;
The rate of B frac{1}{30} job per day.

Say they need t days to complete the project.

According to the stem we have that B works for all t days and A works only for t-10 days, thus frac{1}{20}*(t-10)+frac{1}{30}*t=1 --> t=18days.

Answer: A.

Is this solution Helpfull? Yes (1) | No   

Ajit Singh  (9 years ago)

Let tank filled in x hour then
(x-10)/20+x/30=1
x=18
So project will complete in 18 days

Is this solution Helpfull? Yes (1) | No   

R Santosh Kumar  (8 years ago)

formula for this type of questions is

D= b(n+a)/ (a+b)
b = no of days taken by B to finish the work
a =no of days taken by A to finish the work
n = days before A has left the work
substituting the values we will get

D= 18 days

further queries check website
http://a4academics.com/careers-guidance-jobs/68-quantitative-aptitude/674-time-and-work-shortcuts

Is this solution Helpfull? Yes (1) | No   

Abhishek kumar  (10 years ago)

Ans i....after 5days project will be complete
One day work of A is= 1/20
One day work of B is = 1/30
Work complete in 10 days by A = 1/2
Work complete in 10 days by B=1/3
Remaining work is =1-1/2-1/3=1/6
Time taken by B is =1/6*30=5

Ans is 5Days

Is this solution Helpfull? Yes | No (14)  

ganesh thakur  (9 years ago)

(x-10)/20 +x/30=1
x=18 ans

Is this solution Helpfull? Yes | No   

K Sudharshan reddy  (9 years ago)

27 is the answer

Is this solution Helpfull? Yes | No (4)  

Rajat Jain  (9 years ago)

admin galat ans ko solved likha betha hain

Is this solution Helpfull? Yes | No   

mallikarjuna naik  (9 years ago)

b filled 1/16th of tank in 3hrs
i.e
40
=>1/16th=40
=>full=640
therefor 10,20,40,80,160,320,640
tank can fill in 7hrs

Is this solution Helpfull? Yes | No   

Himani sikarwar  (9 years ago)

its 18 days

Is this solution Helpfull? Yes | No   

smiksha  (9 years ago)

let total days be t.

-> t/20 + t-10/30 =1
->3t+2t-20 /60 =1
->t = 80/5
->t=16 days

Is this solution Helpfull? Yes | No   

vicky  (9 years ago)

(x-10)/20 + x/30 =1
x=18 ANS

Is this solution Helpfull? Yes | No   

ramakrishna  (9 years ago)

10 days only B works , so work by B in 10days=10*(1/30)=1/3
rest work=1-1/3=2/3
together work to complete 2/3 work
so (2/3)*((20*30)/50)=8
so 10+8=18 days

Is this solution Helpfull? Yes | No   

Gaurav Kumar  (9 years ago)

Their 1 day work=(1/20+1/30)=1/12
10 days work = 10/12=5/6 so remaining work is 1/6
it will be done by B alone in 1/6*30 days=5 days
so total days to complete the project will be 10+5 =15

Is this solution Helpfull? Yes | No   

kruparao kommathoti  (9 years ago)

10 days working of A&B is =10(1/10+1/30)
= 2/5
remaining work=1-2/5
=3/5
B alone complete the work is=(3/5)*30
=18days

Is this solution Helpfull? Yes | No   

varaj  (9 years ago)

ans is 15

Is this solution Helpfull? Yes | No (1)  

rajib mistry  (8 years ago)

x-10/20 + x/30 =1
x = 18

Is this solution Helpfull? Yes | No   

happy das  (8 years ago)

The rate of A 120 job per day;
The rate of B 130 job per day.

Say they need t days to complete the project.

According to the stem we have that B works for all t days and A works only for t−10 days, thus 120∗(t−10)+130∗t=1 --> t=18days.

Is this solution Helpfull? Yes | No   

deepmala kumari  (8 years ago)

18 is the answer
27 is wrong

Is this solution Helpfull? Yes | No   

ANKIT  (6 years ago)

Answer is 18 days

Is this solution Helpfull? Yes | No   

Suresh  (6 years ago)

LCM of 20,30 = 60
A's 1 day work = 3
B's 1 day work = 2
A+B's 1 day work = 5

(A+B) * x days + B *10 days = 60
5*x + 2*10 = 60
5x = 40
x = 8

total days = 8+10 =18

Is this solution Helpfull? Yes | No   

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