Q.1. A, B and C can do a piece of work in 20, 30 and 60 days respectively.
In how many days can A do the work if he is assisted by
B and C on every third day?
In how many days can A do the work if he is assisted by
B and C on every third day?
A. 12 days
B. 15 days
C. 16 days
D. 18 days
Answer: Option B
Explanation:
A's 2 day's work =
|  |
1
|
x 2
|  |
=
|
1
|
.
|
20
|
10
|
(A + B + C)'s 1 day's work =
|  |
1
|
+
|
1
|
+
|
1
|  |
=
|
6
|
=
|
1
|
.
|
20
|
30
|
60
|
60
|
10
|
Work done in 3 days =
|  |
1
|
+
|
1
|  |
=
|
1
|
.
|
10
|
10
|
5
|
Now,
|
1
|
work is done in 3 days.
|
5
|
Whole work will be done in (3 x 5) = 15 days.
Q.2.In the beginning, Ram works at a rate such that he can finish a piece of
work in 24 hrs, but he only works at this rate for 16 hrs. After that, he
works at a rate such that he can do the whole work in 18 hrs. If Ram is to
finish this work at a stretch, how many hours will he take to finish this work?
work in 24 hrs, but he only works at this rate for 16 hrs. After that, he
works at a rate such that he can do the whole work in 18 hrs. If Ram is to
finish this work at a stretch, how many hours will he take to finish this work?
a) 12 hrs
b) 18 hrs
c) 11½ hrs
d) 15 hrs
e) 22 hrs
Answer : Option 5
Explanation:Ram’s 16 hr work = 16/24 = 2/3. Remaining work = 1 – 2/3 = 1/3.
Using work and time formula: This will be completed in 1/3 × 18 i.e. 6 hrs.
So, total time taken to complete work = 16 + 6= 22 hrs.
Q.3.A and B can do a piece of work in 4 days, while C and D can do the same
work in 12 days. In how many days will A, B, C and D do it together?
work in 12 days. In how many days will A, B, C and D do it together?
1. 12 days
2. 4 days
3. 3 days
4. 2 days
5. None of these
Answer : Option 3
Explanation:A, B, C and D will together take ¼ + 1/12 = 4/12 = 1/3
⇒ 3 days to complete the work.
⇒ 3 days to complete the work.
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