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:
347 comments Page 6 of 35.
Jyothi said:
4 years ago
I am not getting. How 1-7/15? Explain, please.
(3)
AKT said:
4 years ago
Thanks everyone for explaining the answer.
(3)
Sajid said:
10 months ago
(+1-7/15).
(-*-=+) = 8/15.
(-*-=+) = 8/15.
(3)
Deepa said:
2 decades ago
Can you explain how 7/60 came?
(2)
Haphyz said:
1 decade ago
When dealing with addition or subtraction of fractions you consider the denominators i.e
15&20 and then you find the L.C.M which is 60 or multiply them together.
15*20 = 300 so,
(1/15 + 1/20)/300 = (20 + 15)/300.
=25/300 reduce to the lowest term and you get 7/60.
This 7/60 is the amount of work A & B will complete in one day.
Hence for 4 days we have;
7/60 * 4 = 7/15 of the total work.
Since we don't know the real value of the total work we then assume total work to be done to be 1.
Therefore,
Remaining work left will be,
1- (work done)
1-7/15 ; the denominator here is 15 & 1 (since 1 =1/1).
Do the math and you get our final answer to be 8/15.
NOTE !
If you are subtracting a fraction from a whole number, just multiply the denominator by the whole number and then subtract from the numerator. The same rule applies for addition.
15&20 and then you find the L.C.M which is 60 or multiply them together.
15*20 = 300 so,
(1/15 + 1/20)/300 = (20 + 15)/300.
=25/300 reduce to the lowest term and you get 7/60.
This 7/60 is the amount of work A & B will complete in one day.
Hence for 4 days we have;
7/60 * 4 = 7/15 of the total work.
Since we don't know the real value of the total work we then assume total work to be done to be 1.
Therefore,
Remaining work left will be,
1- (work done)
1-7/15 ; the denominator here is 15 & 1 (since 1 =1/1).
Do the math and you get our final answer to be 8/15.
NOTE !
If you are subtracting a fraction from a whole number, just multiply the denominator by the whole number and then subtract from the numerator. The same rule applies for addition.
(2)
Yusuf said:
4 years ago
A+b 1 days work =7/60.
(2)
Sundar said:
2 decades ago
@Poorni:
The total work = 1;
Work done by A and B in 4 days = 7/15.
Therefore, the pending work = 1 - 7/15 = 0.533333333... (or) 8/15.
Hope this help you. Have a nice day!
The total work = 1;
Work done by A and B in 4 days = 7/15.
Therefore, the pending work = 1 - 7/15 = 0.533333333... (or) 8/15.
Hope this help you. Have a nice day!
(1)
Appu said:
2 decades ago
@Deepa
(1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
I think your doubt is clear now.
(1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
I think your doubt is clear now.
(1)
Beer ibrahim said:
2 decades ago
Why (1-7/15) is applied ?
(1)
Sundar said:
2 decades ago
@Beer Ibrahim
Q: Why (1-7/15) is applied ?
Ans: To calculate the work remaining. Work remaining = 8/15.
Note: From the above answer, we can say 15/8 days required to
complete the remaining work by A and B.
Hope this will help you. Have nice day!
Q: Why (1-7/15) is applied ?
Ans: To calculate the work remaining. Work remaining = 8/15.
Note: From the above answer, we can say 15/8 days required to
complete the remaining work by A and B.
Hope this will help you. Have nice day!
(1)
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