Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 1)
1.
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 :
Answer: Option
Explanation:
| 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 |
Discussion:
344 comments Page 34 of 35.
Anonym said:
1 year ago
A, completes the work in 15 days so, the work done by A in 1 day = 1/15.
Similarly, B completes the work in 20 days therefore work done by B in 1 day = 1/20.
A and b work together = 1/15+1/20 i.e. => 14/120 => 7/60.
Now, they both worked for 4 days which will be = 4*7/60 => 7/15.
Let's suppose the total work is x and they have already worked for 4 days.
Therefore remaining work is x -7/15 (for more clarity take x-7/15 = 0) => 8/15.
Similarly, B completes the work in 20 days therefore work done by B in 1 day = 1/20.
A and b work together = 1/15+1/20 i.e. => 14/120 => 7/60.
Now, they both worked for 4 days which will be = 4*7/60 => 7/15.
Let's suppose the total work is x and they have already worked for 4 days.
Therefore remaining work is x -7/15 (for more clarity take x-7/15 = 0) => 8/15.
(25)
Bha said:
12 months ago
Thanks all for explaining the answer.
(23)
Vishnu said:
12 months ago
A->15.
B->20.
LCM of 15,20 is 60.
A can do 4 parts and B can do 3 parts.
A and B together complete 7 parts in 1 day.
for 4 days 28 parts can complete.
60-28 = 32(leftover work).
32/60 = 8/15.
B->20.
LCM of 15,20 is 60.
A can do 4 parts and B can do 3 parts.
A and B together complete 7 parts in 1 day.
for 4 days 28 parts can complete.
60-28 = 32(leftover work).
32/60 = 8/15.
(268)
Hari said:
11 months ago
@Vishnu.
Can you explain the process in detail please?
Can you explain the process in detail please?
(14)
Irfan said:
11 months ago
How to find out the remaining work? Please explain.
(43)
Sree said:
8 months ago
How 7/60 came? please anyone explain to me?
(33)
Sravanthi tolusuri said:
6 months ago
LCM of 15,20 = 60
days * efficiency = work so, 15 * 4 = 60 20 * 3 = 60.
Efficiencies are 4+3 =7,
They worked for 4 days 7*4 =28.
Total work =60,
60 - 28 =32.
Then the remaining work = 32/60 = 8/15.
days * efficiency = work so, 15 * 4 = 60 20 * 3 = 60.
Efficiencies are 4+3 =7,
They worked for 4 days 7*4 =28.
Total work =60,
60 - 28 =32.
Then the remaining work = 32/60 = 8/15.
(116)
Sajid said:
6 months ago
(+1-7/15).
(-*-=+) = 8/15.
(-*-=+) = 8/15.
(3)
Syam said:
6 months ago
@Sree.
15 is written as = 5 * 3 and 20 is written as 2^2 *5 then 5 is the common then from 15 take 3 and 20 take 2 square, then 4*3*5=60 then 1 * 4/15 * 4 = 4/60 and for 1/20 =1 * 3/20 * 3 = 3/60.
Then the final answer is 4/60 + 3/60 = 7/60.
15 is written as = 5 * 3 and 20 is written as 2^2 *5 then 5 is the common then from 15 take 3 and 20 take 2 square, then 4*3*5=60 then 1 * 4/15 * 4 = 4/60 and for 1/20 =1 * 3/20 * 3 = 3/60.
Then the final answer is 4/60 + 3/60 = 7/60.
(10)
Guna said:
4 months ago
Agree, the answer is D.
(3)
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