Time and Work
Q1
12 man can do a piece of work in 25 days.How long will 10 men take to complete the work?
Ans: 12 X 25 / 10 = 30
Q2
30 man can do a piece of work in 36 days.What is the number of men needed to complete the same work in 24 days?
Ans: 30 X 36 / 24 = 45
Q3
12 man can do a piece of work in 18 days.What is the extra number of men needed to complete the same work in 8 days?
Ans: The number of men needed to complete the work in 8 days = 12 X 18 / 8 = 27
Number of men needed extra = 27 - 12 = 15
Q4
80 man can do a piece of work in 90 days.If 20 more men joined with them how long will take to complete the work?
Ans: 80 X 90 / (80+20) = 72 days
Q5
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is ?
Ans:
A's 1 day's work = |
1 |
; |
|
15 |
|
B's 1 day's work = |
1 |
; |
|
20 |
|
(A + B)'s 1 day's work = |
|
1 |
+ |
1 |
|
= |
7 |
. |
|
15 |
20 |
60 |
(A + B)'s 4 day's work = |
|
7 |
x 4 |
|
= |
7 |
. |
|
60 |
15 |
|
Therefore, Remaining work = |
|
1 - |
7 |
|
= |
8 |
. |
|
15 |
15 |
Q6
A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:
Ans:
(A + B + C)'s 1 day's work = |
1 |
, |
|
4 |
|
A's 1 day's work = |
1 |
, |
|
16 |
|
B's 1 day's work = |
1 |
. |
|
12 |
|
C's 1 day's work = |
1 |
- |
|
1 |
+ |
1 |
|
= |
|
1 |
- |
7 |
|
= |
5 |
. |
|
4 |
16 |
12 |
4 |
48 |
48 |
|
So, C alone can do the work in |
48 |
= 9 |
3 |
days. |
|
5 |
5 |
Q7
|
If 6 men and 8 boys can do a piece of work in 10 days while 26 men and 48 boys can do the same in 2 days, the time taken by 15 men and 20 boys in doing the same type of work will be: Ans:
15 men and 20 boys can do the work in 4 days. Q8
|
