Hii frnds sorry for disturbing.
Please slove the mark questions only.
Please
Answers
1
1.a). As in 4.5 days 'A' can do a job. ( 4---- = 9/2 = 4.5 )
2
So, in 1 day 'A' will complete 1/4.5 part of that work.
= 10/45 part of the work
= 2/9 part of the work.
As in 9 days 'B' can do that job.
so,in 1 day 'B' will do 1/ 9 part of that work.
According to question,
If they work together.So work done by them in 1 day = ( 2/9 + 1/9 )
= 3/9 = 1/3.
If 1/3 part of the work can be done by them in 1 day.
So, to do 1 work they will take 1* 3 days = 3 days.
In 3 days 'A' and 'B' together can do that job.
(b).
Work done by 'A' in 3 days = ( 2/9) * 3 = 2/3.
Work done by 'B' in 3 days = ( 1/9)*3= 1/3.
Let 'A's share will be 'X' and 'B's share be 'Y'.
= 2/3 : 1/3 :: X : Y
= 2 : 1 :: X : Y
2 Y = X. ---- equation 1 { Product of extremes = Product of mean }
A/Q,
X + Y = Rs.900 ---------------- equation 2
By putting the value of 'X' in the above equation 2,
2 Y + Y = Rs. 900
3 Y = Rs. 900
Y = Rs.900 / 3
Y = Rs. 300
By putting the value of 'Y' in equation 1,
X = 2 Y
X = 2 * Rs. 300
X = Rs.600
So, A's share is Rs.600 and that's of 'B' is Rs. 300.
_______________________________________________________
5. If in 1 day 'A' can dig 1/12 part of a trench.
If in 3 days 'B' can dig 1/6 part of the trench.
So, in 1 day 'B' will dig 1/ 6 * 3 = 1/18 part of the trench.
So,if they work together then, in 1 day they will dig ( 1/18 + 1/12 ) part.
2 + 3
= ( -------------- ) part.
36
= 5/36 part.
If they can dig 5/36 part of the trench in 1 day.
So, to dig whole trench they will take 36/5 days.
= 7.2 days.
________________________________________________________
7. As, in 6 days 'A' can do a job.
So, in 1 day 'A' will do 1/6 part of the job.
As, in 8 days 'B' can do that job.
So, in 1 day 'B' will do 1/8 part of the job.
So,when they work together then work done by them in 1 day = 1/6 + 1/8 part
4 + 3
= -------------- part
24
= 7/24 part of the job.
So,work completed by them in 2 days = 7 * 2 /24 = 7/12 part of the job.
Now,
Left work = Total work - work done by them in 2 days.
= 1 - 7/12
12 - 7
= ---------- = 5/12 part of the work.
12
As, 'A' can do 1 job in 6 days.
So, 'A' will do 5/12 part of the work in 6 * 5 /12 days = 5/2 days = 2.5 days.
_______________________________________________________
11. If in 12 hours 'A' can do a work.
So, in 1 hour 'A' will do 1/12 part of the work.
If in 20 hours 'B' can do a work.
So, in 1 hour 'B' will do 1/20 part of the work.
If in 30 hours 'C' can do a work.
So, in 1 hour 'C' will do 1/30 part of the work.
Work done by them together in 1 hour = ( 1/12 + 1/20 + 1/30 )
5 + 3 + 2
= ( ------------------------- )
60
= 10/60 = 1/6.
If they can do 1/6 part of a job in 1 hour.
So, to do 1 work , they will take 1 * 6 hour = 6 hour.
__________________________________________________________
13. If in 6 days ( A + B ) can do a job.
So, in 1 day ( A + B ) will do 1 / 6 part of the job.
If in 9 days ( B + C ) can do that job.
So, in 1 day ( B + C ) will do 1 / 9 part of the job.
If in 12 days ( A + C ) can do a job.
So, in 1 day ( A + C ) can do 1/12 part of them.
Work done by these three groups of people together in 1 day = 1/6 + 1/9 + 1/12
6 + 4 + 3
( A + B ) + ( B + C ) + ( C + A ) = ------------------------------- part of the work.
36
A + B + B + C + C + A = 13 / 36 part of the work.
2 A + 2 B + 2 C = 13 / 36 part of the work.
2 ( A + B + C ) = 13 /36 part of the work.
A + B + C = 13 / 36 * 2 part if the work
A + B + C = 13 / 72 part of the work.
If ( A + B + C ) can do 13/72 part of the work in 1 day.
So, ( A + B + C ) can do 1 work in 72/13 days.
☻☻☻☻☻☻☻☻
Answer:
Heya Sapna di,
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
1
1.a). As in 4.5 days 'A' can do a job. ( 4---- = 9/2 = 4.5 )
2
So, in 1 day 'A' will complete 1/4.5 part of that work.
= 10/45 part of the work
= 2/9 part of the work.
As in 9 days 'B' can do that job.
so,in 1 day 'B' will do 1/ 9 part of that work.
According to question,
If they work together.So work done by them in 1 day = ( 2/9 + 1/9 )
= 3/9 = 1/3.
If 1/3 part of the work can be done by them in 1 day.
So, to do 1 work they will take 1* 3 days = 3 days.
In 3 days 'A' and 'B' together can do that job.
(b).
Work done by 'A' in 3 days = ( 2/9) * 3 = 2/3.
Work done by 'B' in 3 days = ( 1/9)*3= 1/3.
Let 'A's share will be 'X' and 'B's share be 'Y'.
= 2/3 : 1/3 :: X : Y
= 2 : 1 :: X : Y
2 Y = X. ---- equation 1 { Product of extremes = Product of mean }
A/Q,
X + Y = Rs.900 ---------------- equation 2
By putting the value of 'X' in the above equation 2,
2 Y + Y = Rs. 900
3 Y = Rs. 900
Y = Rs.900 / 3
Y = Rs. 300
By putting the value of 'Y' in equation 1,
X = 2 Y
X = 2 * Rs. 300
X = Rs.600
So, A's share is Rs.600 and that's of 'B' is Rs. 300.
_______________________________________________________
5. If in 1 day 'A' can dig 1/12 part of a trench.
If in 3 days 'B' can dig 1/6 part of the trench.
So, in 1 day 'B' will dig 1/ 6 * 3 = 1/18 part of the trench.
So,if they work together then, in 1 day they will dig ( 1/18 + 1/12 ) part.
2 + 3
= ( -------------- ) part.
36
= 5/36 part.
If they can dig 5/36 part of the trench in 1 day.
So, to dig whole trench they will take 36/5 days.
= 7.2 days.
________________________________________________________
7. As, in 6 days 'A' can do a job.
So, in 1 day 'A' will do 1/6 part of the job.
As, in 8 days 'B' can do that job.
So, in 1 day 'B' will do 1/8 part of the job.
So,when they work together then work done by them in 1 day = 1/6 + 1/8 part
4 + 3
= -------------- part
24
= 7/24 part of the job.
So,work completed by them in 2 days = 7 * 2 /24 = 7/12 part of the job.
Now,
Left work = Total work - work done by them in 2 days.
= 1 - 7/12
12 - 7
= ---------- = 5/12 part of the work.
12
As, 'A' can do 1 job in 6 days.
So, 'A' will do 5/12 part of the work in 6 * 5 /12 days = 5/2 days = 2.5 days.
_______________________________________________________
11. If in 12 hours 'A' can do a work.
So, in 1 hour 'A' will do 1/12 part of the work.
If in 20 hours 'B' can do a work.
So, in 1 hour 'B' will do 1/20 part of the work.
If in 30 hours 'C' can do a work.
So, in 1 hour 'C' will do 1/30 part of the work.
Work done by them together in 1 hour = ( 1/12 + 1/20 + 1/30 )
5 + 3 + 2
= ( ------------------------- )
60
= 10/60 = 1/6.
If they can do 1/6 part of a job in 1 hour.
So, to do 1 work , they will take 1 * 6 hour = 6 hour.
__________________________________________________________
13. If in 6 days ( A + B ) can do a job.
So, in 1 day ( A + B ) will do 1 / 6 part of the job.
If in 9 days ( B + C ) can do that job.
So, in 1 day ( B + C ) will do 1 / 9 part of the job.
If in 12 days ( A + C ) can do a job.
So, in 1 day ( A + C ) can do 1/12 part of them.
Work done by these three groups of people together in 1 day = 1/6 + 1/9 + 1/12
6 + 4 + 3
( A + B ) + ( B + C ) + ( C + A ) = ------------------------------- part of the work.
36
A + B + B + C + C + A = 13 / 36 part of the work.
2 A + 2 B + 2 C = 13 / 36 part of the work.
2 ( A + B + C ) = 13 /36 part of the work.
A + B + C = 13 / 36 * 2 part if the work
A + B + C = 13 / 72 part of the work.
If ( A + B + C ) can do 13/72 part of the work in 1 day.
So, ( A + B + C ) can do 1 work in 72/13 days.