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 29 of 35.
Manoj said:
1 decade ago
35/300=7/60 please explain it.
Manoj said:
1 decade ago
Can you explain how did 7/60 come?
Rinkesh said:
1 decade ago
Very simple,
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
15+20=35
15*20=300
35/300=7/60
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
Shro said:
1 decade ago
Thanku Prakash :).
K.Nirdesh said:
1 decade ago
1/50+1/20) = (20+15)/300 //This get by cross multiplication.
= 35/300
= 7/60.
why we should Division do for (20+15)/300, how did the 300 is come?
= 35/300
= 7/60.
why we should Division do for (20+15)/300, how did the 300 is come?
Razeena said:
1 decade ago
Hi friends,
A's 1 day work=1/15; B's 1 day work=1/20
OK.Then we calculate how much A + B can do in 1 day.
ie 1/15 + 1/20 ( in fraction if denominator is different first we find the l.c.m of denominator).so we calculate the l.c.m of 15 and 20 ie 60(15 and 20 is divided by 5 we get the answer 3 and 4 so we find l.c.m by multiplying 5*3*4=60).1/15*60+1/20*60=4+3/60=7/60.
if A and B do work in 4 days=7/60*4=7/15
Remaining work=1-7/15 = 8/15 [ (15*1-7)/15 = 8/15 ].
A's 1 day work=1/15; B's 1 day work=1/20
OK.Then we calculate how much A + B can do in 1 day.
ie 1/15 + 1/20 ( in fraction if denominator is different first we find the l.c.m of denominator).so we calculate the l.c.m of 15 and 20 ie 60(15 and 20 is divided by 5 we get the answer 3 and 4 so we find l.c.m by multiplying 5*3*4=60).1/15*60+1/20*60=4+3/60=7/60.
if A and B do work in 4 days=7/60*4=7/15
Remaining work=1-7/15 = 8/15 [ (15*1-7)/15 = 8/15 ].
Sai kishore said:
1 decade ago
Still I have confusion. How 7/60 comes?
Bandna said:
1 decade ago
Good shweta.
Santhi said:
1 decade ago
Good explanation swetha.
Ram said:
1 decade ago
Hi friends..........
A can do wrk in 15 dayz ;
b Can do wrk in 20 dayz;
then LCM of A&B=7/60;
Explain:
=1/15+1/20
=[(4/4*15)+(3/3*20)]
=(4/60)+(3/60)
=3+4/60
=7/60
If A and B do wrk in 4 day=(7/60 *4 )
=7/15
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
Its easy for ur understanding...............
A can do wrk in 15 dayz ;
b Can do wrk in 20 dayz;
then LCM of A&B=7/60;
Explain:
=1/15+1/20
=[(4/4*15)+(3/3*20)]
=(4/60)+(3/60)
=3+4/60
=7/60
If A and B do wrk in 4 day=(7/60 *4 )
=7/15
work is 1 so=1-7/15
=15-7/15
Ans is = 8/15
Its easy for ur understanding...............
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers