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 9 of 35.
SUNDARA said:
8 years ago
A & B together requires 1/15+1/20=7/60 or 60/7days =8 4/7 days to complete the work.
After 4 days work, pending work is 8 4/7 -4=4 4/7days work.
= 4 4/7 divide by 8 4/7=32/7 divide 60/7=32/60=8/15 work pending.
After 4 days work, pending work is 8 4/7 -4=4 4/7days work.
= 4 4/7 divide by 8 4/7=32/7 divide 60/7=32/60=8/15 work pending.
Tinu said:
1 decade ago
Because a work is calculated as 1.
If any value coming under fraction it comes between 0 to 1 so only.
Like 15/15 = 1.
Likewise Here we have 7/15 only, we need to know the remaining.
15/15-7/15 = 15-7/15 = 8/15.
If any value coming under fraction it comes between 0 to 1 so only.
Like 15/15 = 1.
Likewise Here we have 7/15 only, we need to know the remaining.
15/15-7/15 = 15-7/15 = 8/15.
Er.Ketan Patel said:
1 decade ago
Take LCM is 60 mean total work done is 60.
It mean "a" can do 4 unit/day, "b" can do 3 unit/day.
Total 3+4 = 7/60.
Both do work together 4 days mean (7*4=28).
They complete the work 28 (60-28=32).
32/60 = 8/15.
It mean "a" can do 4 unit/day, "b" can do 3 unit/day.
Total 3+4 = 7/60.
Both do work together 4 days mean (7*4=28).
They complete the work 28 (60-28=32).
32/60 = 8/15.
Swetha said:
6 years ago
We know A done his work in 15 days and B in 20 days so total work is we take as 1.work is inversely proportion to days 1÷15 +1÷20=(15+20)/15x20=35/300=7/60=7x4/60=28/60=1-28/60=8/15.
Here 1 indicates total work.
Here 1 indicates total work.
Aravind said:
1 decade ago
We have to divide the denominator by its common divisible number and cross multiply it in numerator so you will get 7 then mutilply the highest remainder of lcm with the lowest denominator. You will get answer.
Jinto said:
10 years ago
(A+B) 's 1 day's work = 7/60.
So (A+B) can finish the work in 60/7 day.
(A+B) 's 4 day's work = 7/15.
So remaining work = (60/7) - (7/15).
Is this correct? Why remaining work = (1-7/15), from where 1 came?
So (A+B) can finish the work in 60/7 day.
(A+B) 's 4 day's work = 7/15.
So remaining work = (60/7) - (7/15).
Is this correct? Why remaining work = (1-7/15), from where 1 came?
Jigme wangchuk said:
4 years ago
Simple method.
A = 15 days,
B = 20 days,
No days of work together (A+B) = 4 days,
Fraction of work = 4* sum/product.
= 4*(15+20/15*20) =140/300 simplify = 7/15.
Now, remaining fraction of work = 1-7/15
= 8/15.
A = 15 days,
B = 20 days,
No days of work together (A+B) = 4 days,
Fraction of work = 4* sum/product.
= 4*(15+20/15*20) =140/300 simplify = 7/15.
Now, remaining fraction of work = 1-7/15
= 8/15.
Mallarapusudhakar said:
1 decade ago
a = 15, b = 20, together c = 4 but LCM of in this 3 numbers is 60.
So a is 15(4), b is 20(3) and c is 4(15).
The first of 2 function is (4+3) remaining c(15).
The total of LCM(60).
15-7 = 8.
8/60 answer.
So a is 15(4), b is 20(3) and c is 4(15).
The first of 2 function is (4+3) remaining c(15).
The total of LCM(60).
15-7 = 8.
8/60 answer.
Mounika said:
1 decade ago
'1' is the total work that has to be done. (It has to be taken by default in time and work).
7/15 is (A+B) 4 day's work.
So, total work- (A+B) 's 4 day's work=work that is left to be done.
1-7/15 = 8/15.
7/15 is (A+B) 4 day's work.
So, total work- (A+B) 's 4 day's work=work that is left to be done.
1-7/15 = 8/15.
Indu said:
1 decade ago
Short trick if you are use to of percentage:
A's 1 day's work = 6.67% (100/15).
B's 1 day's work = 5%.
A+B's 1 day's work = 11.67%.
A+B's 4 day's work = 46.68%.
Remaining... 100-46.68 = 53.33% i.e. 8/15.
A's 1 day's work = 6.67% (100/15).
B's 1 day's work = 5%.
A+B's 1 day's work = 11.67%.
A+B's 4 day's work = 46.68%.
Remaining... 100-46.68 = 53.33% i.e. 8/15.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers