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:
351 comments Page 5 of 36.
Jaiprakash said:
4 months ago
A > 15 both LCM 60.
B > 20.
(A+B ) * 4 = 60.
7 * 4 = 28.
60 - 28/60.
32/60 = 8/15.
B > 20.
(A+B ) * 4 = 60.
7 * 4 = 28.
60 - 28/60.
32/60 = 8/15.
(12)
Syam said:
1 year 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.
(11)
Mish said:
3 years ago
@All.
Why (A+B)'s 4 days of work is calculated?
Why it's not 3,5,6,7 or any other day?
What is the logic behind it?
Why (A+B)'s 4 days of work is calculated?
Why it's not 3,5,6,7 or any other day?
What is the logic behind it?
(10)
Sugan said:
2 years ago
1 (total work) - 7/15 (together completed work in 4 days).
Lcm = 15 then (15/15 -7/15) = 8/15.
Lcm = 15 then (15/15 -7/15) = 8/15.
(8)
Kalai said:
2 years ago
How remaining work =1? Please explain to me.
(7)
Swetha said:
4 years ago
First of all, thank you to explain the method.
I have a doubt that how we know to take (i.e Total work = 60)?
Anyone, please help me to get it.
I have a doubt that how we know to take (i.e Total work = 60)?
Anyone, please help me to get it.
(6)
Sivagami said:
2 years ago
How 7/60 came? Please explain.
(6)
Guna said:
11 months ago
Agree, the answer is D.
(6)
Rakesh said:
2 years ago
1/15+1/20 LCM of this is 60.
So,
(1/15 * 60 + 1/20 * 60)/60we can simplify this you can get (4+3)/60 = 7/60.
So,
(1/15 * 60 + 1/20 * 60)/60we can simplify this you can get (4+3)/60 = 7/60.
(4)
Prasanth.sunny143 said:
1 decade ago
@L Raj Scope
Please understand this concept first.
LET CONSIDER A SIMPLE STATEMENT:
A can do a work in 2 days.
That means A's 1 day work = 1/2.
This is the methodology we wanna apply on the data which is given in question.
From the question.
A (CAN D0 A JOB) ----15 days.
B (CAN DO A JOB) ----20 days.
Therefore by the above concept A's 1 day work = 1/15.
B's 1 day work = 1/20.
Therefore both A&B 1 work = (1/15)+1/20) = 7/60.
NOW READ THE QUESTION.
If A&B work together for 4 days then what the fraction of work left.
Consider:
Total work = 1.
A&B (4 DAYS WORK) = (7/60)*4 = 7/15.
REMAIN B WORK = (TOTAL WORK)-(COMPLETED WORK BY A&B FOR 4 DAYS).
= 1-7/15.
= 8/15.
Hope this is helpful.
Please understand this concept first.
LET CONSIDER A SIMPLE STATEMENT:
A can do a work in 2 days.
That means A's 1 day work = 1/2.
This is the methodology we wanna apply on the data which is given in question.
From the question.
A (CAN D0 A JOB) ----15 days.
B (CAN DO A JOB) ----20 days.
Therefore by the above concept A's 1 day work = 1/15.
B's 1 day work = 1/20.
Therefore both A&B 1 work = (1/15)+1/20) = 7/60.
NOW READ THE QUESTION.
If A&B work together for 4 days then what the fraction of work left.
Consider:
Total work = 1.
A&B (4 DAYS WORK) = (7/60)*4 = 7/15.
REMAIN B WORK = (TOTAL WORK)-(COMPLETED WORK BY A&B FOR 4 DAYS).
= 1-7/15.
= 8/15.
Hope this is helpful.
(3)
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