Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 10)
10.
A machine P can print one lakh books in 8 hours, machine Q can print the same number of books in 10 hours while machine R can print them in 12 hours. All the machines are started at 9 A.M. while machine P is closed at 11 A.M. and the remaining two machines complete work. Approximately at what time will the work (to print one lakh books) be finished ?
Answer: Option
Explanation:
| (P + Q + R)'s 1 hour's work = |  |
1 | + | 1 | + | 1 |  |
= | 37 | . |
| 8 | 10 | 12 | 120 |
| Work done by P, Q and R in 2 hours = | |
37 | x 2 | |
= | 37 | . |
| 120 | 60 |
| Remaining work = | |
1 - | 37 | |
= | 23 | . |
| 60 | 60 |
| (Q + R)'s 1 hour's work = | |
1 | + | 1 | |
= | 11 | . |
| 10 | 12 | 60 |
| Now, | 11 | work is done by Q and R in 1 hour. |
| 60 |
| So, | 23 | work will be done by Q and R in | |
60 | x | 23 | |
= | 23 | hours  2 hours. |
| 60 | 11 | 60 | 11 |
So, the work will be finished approximately 2 hours after 11 A.M., i.e., around 1 P.M.
Discussion:
95 comments Page 2 of 10.
Manju said:
1 decade ago
Thanks naveen sir.
Piyus said:
1 decade ago
Friends
P's 2 hr work = 1/8*2=1/4
rest 3/4 work done by q&r
q+r 1hr = 1/10 + 1/12=11/60 work
3/4 work by q&r=60/11 * 3/4=4.09
The work complete time was 9a.m+4=1p.m
P's 2 hr work = 1/8*2=1/4
rest 3/4 work done by q&r
q+r 1hr = 1/10 + 1/12=11/60 work
3/4 work by q&r=60/11 * 3/4=4.09
The work complete time was 9a.m+4=1p.m
Ramkumar said:
1 decade ago
Can anyone tell
Why you put last step as 9am+4?
Already p, q, r done by 2hrs and (q&r) in 4 hrs know.
Then 2+4=6 only know.
On this step I am in confusion. Help me.
Why you put last step as 9am+4?
Already p, q, r done by 2hrs and (q&r) in 4 hrs know.
Then 2+4=6 only know.
On this step I am in confusion. Help me.
Rahul said:
1 decade ago
All the machines are started at once.
we have got the solution as 4 hrs for both machines q & r
they have started at 9 a.m.
q & r work for 4 hrs
So 9+4=13 i.e,1 p.m.
we have got the solution as 4 hrs for both machines q & r
they have started at 9 a.m.
q & r work for 4 hrs
So 9+4=13 i.e,1 p.m.
Shekar said:
1 decade ago
2(1/8+1/10+1/12)+x(1/10+1/12)=1 we get x value is 2.09. required value is 11am+209=1.09pm,we taken approx value 1pm.
Parveen said:
1 decade ago
Printing Pages in one hour:
P---->12500
Q---->10000
R---->8333
Because p will be closed at 11 A.M so printed pages by P till 11 A.M (12500*2)= 25000
Remaining pages(100000-25000)= 75000
So time taken will be 75000/(10000+8333)= 4 hours(approx.)
9 A.M+ 4 hours= 1.00P.M
P---->12500
Q---->10000
R---->8333
Because p will be closed at 11 A.M so printed pages by P till 11 A.M (12500*2)= 25000
Remaining pages(100000-25000)= 75000
So time taken will be 75000/(10000+8333)= 4 hours(approx.)
9 A.M+ 4 hours= 1.00P.M
Sneha said:
1 decade ago
Can you please explain how 1/8+1/10+1/12= 37/120.
Ajay said:
1 decade ago
Hi I have 1 short cut to this type of problem.
a,b,c have 2hrs time diffrnce,a completed the work at 11am similarly b at 13 and c at 15. So avg of 11, 13, 15 is 13 i.e., 1.00 pm.
a,b,c have 2hrs time diffrnce,a completed the work at 11am similarly b at 13 and c at 15. So avg of 11, 13, 15 is 13 i.e., 1.00 pm.
Alok rai said:
1 decade ago
By using concept of percentage
A's 1 day work=100/8%=12.5%
B's 1 day work=100/10%=10%
C's 1 day work=100/12%=8.5%
(A+B+C)'s 1 day work=12.5+10+8.5=31%
(A+B+C)'s 2 day work=31%*2=62%
remaining work =100%-62%=38%
(B+C)'s 1 day work=10.5%+8.5=19%
Therefore
time taken by A and B to complete the remaining work=38/19=2 hr
hence work finished at 1 pm.
A's 1 day work=100/8%=12.5%
B's 1 day work=100/10%=10%
C's 1 day work=100/12%=8.5%
(A+B+C)'s 1 day work=12.5+10+8.5=31%
(A+B+C)'s 2 day work=31%*2=62%
remaining work =100%-62%=38%
(B+C)'s 1 day work=10.5%+8.5=19%
Therefore
time taken by A and B to complete the remaining work=38/19=2 hr
hence work finished at 1 pm.
Kumar said:
1 decade ago
@sneha Its just taking Lcm for 1/8+1/10+1/12 you il get 37/120.
Lcm for 8, 10, 12 is 120.
8 goes 15 times in 120 and 10 goes 12 times in 120 and 12 goes 10 times in 120.
By adding 15+10+12=37 you will get.
Hope you got it.
Lcm for 8, 10, 12 is 120.
8 goes 15 times in 120 and 10 goes 12 times in 120 and 12 goes 10 times in 120.
By adding 15+10+12=37 you will get.
Hope you got it.
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