Aptitude - Time and Work - Discussion

A can complete the work in 15 days.
B can complete the work in 10 days.
Assume Total work LCM(15,10) = 30 units
So, A's efficiency(1 day work) = 30/15 = 2 units
B's efficiency(1 day work) = 30/10 = 3 units

Now, Let the whole work was completed in x days.
Work completed by A and B together in 2 days = (Efficiency of A and B) * Days
= (2+3) * 2 = 10 units
Remaining work is completed by A (B had left) = Efficiency of A * (x - 2)
= 2 * (x - 2) Since, Number of days left = x - 2
10 units + 2*(x - 2) = Total work
10 + 2x - 4 = 30
=> x = 12 days.

A = 15.
B = 10.

Work per day = 1.

We can get 1/15 and 1/10.

We can solve it like this:.
= ( (1 * 10) + (15 * 10) ) + ((1 * 15) + (15 * 10) ) ----> Cross Multiply.

We will get: then add.

= 10/150 + 15/150.

Then simplify:
= 25/150.
= 1/6.

Then minus the number of work per day.

= 1/6 - 1.

You will get the following answer then multiply to the number of work of the person had left.

= 5/6 * 1/10 ---> Cross Multiply.
= 50/6 ---> Get the whole number.
= 12.

A can do in 15 days.
B can do in 10 days.
Total work=lcm(30).
So, A 1 day work=30/15=2 units.
B 1 day work=30/10=3 units.
B worked for 2 days and left = 2*3=6.
The remaining work left is = 30-6=24.
Now, A alone can do 24 units =24/2=12 days.
Thus,the whole work is completed in 12 days.

Hope, it clears.

Take a look at easy method:-

A-15 days.
B-10 days.

Lcm of 10 and 15 =30.

A's 1 day work= 30/15=2.
B's 1 day work=30/10=3.

B left after 2 days, so,
B's 2 day work=3 2=6.

Now work left for A= 30-6=24.

Days required by A to complete the work= 24÷2= 12.
So, 12 days are the required answer.

A -15days
B -10days
LCM - 30
A - 2unit/day
B - 3unit/day

A + B = 5unit/day
They worked for 2days, so 2 * 5 = 10,
Remaining 10 - 30 = 20,
A alone do the remaining in 20 ÷ 2 = 10,
So the total work get completed in 10 + 2 = 12,
Bcoz Already A+B worked for 2days,now A alone in 10 days.

A -15 days.
B- 10.

A&B- 6.
The lcm of 15,10 ,6= 30,
A can do 2 in 1 day,
B can 3 in 1 day,
together 5 in 1 day,

Given the first two days, they worked together means 10w is done.
Remaining is 20w done by A in 10 day.
So 10 + 2(starting 2 day by A,b) = 12.

A's 1 day work=1/15
B's 1 day work=1/10
now,B left after 2 days then 1/10*2=1/5
remaining work is (1-1/5)=4/5
4/5 work is left by B then A has to do remaining work (1/15*5/4)=1/12 this is A's 1 day work after B left work
now A completes work in 12 days...

Guys at last 2 are added. Look at questions carefully. Because the total time to complete the work is asked. Not time is taken by a to complete the job. So total day is 10 + 2=12.

Hope you are done what it now! Cheers.

This problem as it is 11th problem.

B did work 2 days out of 10 days = 2/10 = 1/5.
Remaining work = 1-1/5 = 4/5.
A did 1/15 th work in 1 day.
A did 4/5 th work in ? days.
Cross multiply,

? days = 4/5* 15= 12 days.

a=15 days = 1/15 work for 1 day,
b=10 days =1/10 work for 1 day,
So in 2 days, 1/3 work is done.
1-1/3 = 2/3 work is remaining,
1/15 work 1 day,
2/3 work ? day,
10 days for A.

Total days are 10+2 = 12.