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 10 of 35.
Naren said:
10 years ago
Dear friends, I have the doubt that why we take the total work as 1 instead of taking 60.
We take LCM of 15 & 20 as 60. So we consider 60 units as the total work. So we should take 60? Help me please.
We take LCM of 15 & 20 as 60. So we consider 60 units as the total work. So we should take 60? Help me please.
Kennethy said:
9 years ago
@ Vishwanath.
7/60 * 4 = 7/15.
This is how;
It's like multiplying 7/60 by 4/1 = 7 * 4/60 * 1
This gives us 28/60.
We get a common divisor of the numerator and denominator which is 4.
Hence it is 7/15.
7/60 * 4 = 7/15.
This is how;
It's like multiplying 7/60 by 4/1 = 7 * 4/60 * 1
This gives us 28/60.
We get a common divisor of the numerator and denominator which is 4.
Hence it is 7/15.
Rahul Manjhi said:
8 years ago
If A can do work in 15days then in 4days will be=4/15,
Similarly, if B can do work in 20days then 4days will be=4/20=1/5,
Therefore adding A and b together=4/15+1/5=7/15,
Now remaining work=1-7/15=8/15.
Similarly, if B can do work in 20days then 4days will be=4/20=1/5,
Therefore adding A and b together=4/15+1/5=7/15,
Now remaining work=1-7/15=8/15.
Mogarg said:
7 years ago
@All
Here is the Concept of 1.
If a can do work in 5 days, then,
In one day = 1/5.
In 5 days = 1/5+1/5+1/5+1/5+1/5.
= 5/5 =1.
the concept of 1 means total work, not a day so assume our total work 1.
Here is the Concept of 1.
If a can do work in 5 days, then,
In one day = 1/5.
In 5 days = 1/5+1/5+1/5+1/5+1/5.
= 5/5 =1.
the concept of 1 means total work, not a day so assume our total work 1.
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)
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)
Sweety said:
1 decade ago
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 = (7x1) = 7.
60 4 15.
Therefore, Remaining work = (1+7) = 8.
15 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 = (7x1) = 7.
60 4 15.
Therefore, Remaining work = (1+7) = 8.
15 15.
Mitsuna said:
10 years ago
"From the above answer, we can say 15/8 days required to.
Complete the remaining work by A and B".
Can you please calculate this in whole number so that we can assume the exact days remaining?
Complete the remaining work by A and B".
Can you please calculate this in whole number so that we can assume the exact days remaining?
Giri said:
2 years ago
Just take LCM on 15 and 20 of 60.
Total work 60.
Capacity A 4 and capacity B 3 total 7.
They both worked together for 4 days and completed work 28.
Remaining work 32/60,
So, the Answer 8/15.
Total work 60.
Capacity A 4 and capacity B 3 total 7.
They both worked together for 4 days and completed work 28.
Remaining work 32/60,
So, the Answer 8/15.
(60)
Urmm said:
1 decade ago
L.C.M. of 15 & 20 are 60
and 60/15=4
and 60/20=3
so 4+3=7 as numerator
and 60 is denominator
OR
1/15+1/20=[(1*20)+(1*15)]/300=(20+15)/300=35/300=7/60
35 devide by 5 and 300 devide by 5
and 60/15=4
and 60/20=3
so 4+3=7 as numerator
and 60 is denominator
OR
1/15+1/20=[(1*20)+(1*15)]/300=(20+15)/300=35/300=7/60
35 devide by 5 and 300 devide by 5
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