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 8 of 10.
Deepak said:
1 decade ago
A and B can done a work in 10 days, B and C done same work in 18 days,
If A did work 4 days, B did 8 days and C did 14 days. How much days C takes to complete same work?
If A did work 4 days, B did 8 days and C did 14 days. How much days C takes to complete same work?
Abhay said:
1 decade ago
A simple time saving shortcut :
P= 100000= 8hrs So Per hr work : 12500.
Q= 100000= 10 hrs So per hr work : 10000.
R =100000=12 hrs So Per hr : 8334.
9AM- 10 Am =12500+10000+8334=30834.
10 AM -11 Am = 30834 :: Total work completed: 30834+30834= 61668.
11AM-12PM = 61668+ 18334= 80002.
So definitely we require more time than 12PM. Just look at the option and click.
P= 100000= 8hrs So Per hr work : 12500.
Q= 100000= 10 hrs So per hr work : 10000.
R =100000=12 hrs So Per hr : 8334.
9AM- 10 Am =12500+10000+8334=30834.
10 AM -11 Am = 30834 :: Total work completed: 30834+30834= 61668.
11AM-12PM = 61668+ 18334= 80002.
So definitely we require more time than 12PM. Just look at the option and click.
Girija said:
1 decade ago
Hi @Ajay,
A, B, C have 2hrs time difference.
In the question they told p machine closed at 11:00 am, that means it worked for only 2 hrs, it doesn't mean that P, Q, are machines have 2hrs time difference.
Could you explain the short cut indeed?
A, B, C have 2hrs time difference.
In the question they told p machine closed at 11:00 am, that means it worked for only 2 hrs, it doesn't mean that P, Q, are machines have 2hrs time difference.
Could you explain the short cut indeed?
Kumar said:
1 decade ago
@Sowjanya Hey friends. Can any one suggest why 60/11 is multiplied with 23/60?
Ans:See 23/60 is the Remaining Work and 60/11 is the Time taken to do Remaining work.
By multiplying both we will get total time=23/11.
Hope you Got it.
Ans:See 23/60 is the Remaining Work and 60/11 is the Time taken to do Remaining work.
By multiplying both we will get total time=23/11.
Hope you Got it.
Kumar said:
1 decade ago
@vachu P is working for 2 hrs it is mentioned indirectly.
In question they told all machines started at 9 am and p closed at 11 am means p's Time is 9-10 1 hour and 10-11 2 hrs Total p's machine Time is 2 Hours Right.
In question they told all machines started at 9 am and p closed at 11 am means p's Time is 9-10 1 hour and 10-11 2 hrs Total p's machine Time is 2 Hours Right.
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.
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.
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.
Sneha said:
1 decade ago
Can you please explain how 1/8+1/10+1/12= 37/120.
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
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