Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 4)
4.
A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
Answer: Option
Explanation:
Ratio of times taken by A and B = 1 : 3.
The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.
If difference of time is 2 days, B takes 3 days.
| If difference of time is 60 days, B takes |  |
3 | x 60 |  |
= 90 days. |
| 2 |
So, A takes 30 days to do the work.
| A's 1 day's work = | 1 |
| 30 |
| B's 1 day's work = | 1 |
| 90 |
| (A + B)'s 1 day's work = | |
1 | + | 1 | |
= | 4 | = | 2 |
| 30 | 90 | 90 | 45 |
 A and B together can do the work in |
45 | = 22 | 1 | days. |
| 2 | 2 |
Discussion:
281 comments Page 3 of 29.
Nagarjun said:
1 decade ago
@Vikas
Its just cross multiplication.
If the difference is 2 days then b takes 3 days
If the difference is 60 days then b takes x days
Hence, x= (60*3)/2.
I think you got it now.
Its just cross multiplication.
If the difference is 2 days then b takes 3 days
If the difference is 60 days then b takes x days
Hence, x= (60*3)/2.
I think you got it now.
Naresh kumar said:
1 decade ago
Thank you guys.
Malini said:
1 decade ago
Sheetal thanks a lot dear. This short cut is very much easy.
Baskar said:
1 decade ago
@bharathi
i think u r in confusion..
just know dat
work = day..
1 day = 2/45 works..
in ques ask abt "work"?
den cross mul
1 work = 45/2 days..
now u got it
i think u r in confusion..
just know dat
work = day..
1 day = 2/45 works..
in ques ask abt "work"?
den cross mul
1 work = 45/2 days..
now u got it
G.P. said:
1 decade ago
SIMPLE AND BEST WAY
since a is thrice better than b
hence a:b=1:3
similarly a takes 60 days less than b
hence a:b=(b-60):b=1;3
cross multiplication n we get
3b-180=b hence b=90days hence a=30days
1/90+1/60=4/90 hence total daysreciprocal 90/4=45/2
since a is thrice better than b
hence a:b=1:3
similarly a takes 60 days less than b
hence a:b=(b-60):b=1;3
cross multiplication n we get
3b-180=b hence b=90days hence a=30days
1/90+1/60=4/90 hence total daysreciprocal 90/4=45/2
Nishant said:
1 decade ago
@ G.P.
Thanks. I like the way you solve it.
Thanks. I like the way you solve it.
Balaji said:
1 decade ago
Showry you explained superbly.
Prathyusha said:
1 decade ago
SIMPLE AND NICE EXPLANATION!... @KUMAR
Vani said:
1 decade ago
Showry's explanation is good.
Siva said:
1 decade ago
Hi Guys,
I think following simple method (alternate) will make you more clear,
A can complete work in N days => A's 1day work = (1/N)----1
B can complete work in n days => B's 1day work = (1/n)----2
Given data,
A thrice as B so , A=3B
A complete work 60 days less than B so, (N=n-60)
Apply in 1 & 2
A's 1day work = (1/(n-60))-----3
B's 1day work = (1/n)--------4
we know that A=3B ; B=(1/n) so,Apply B in A we get[A=3/n]
Apply in 3
3/n=(1/(n-60))
by solving,
3n-180=n
n=90
so, B can complete work in 90 Days => B's 1 Day work =(1/90)
we know that N=n-60,
so, A can complete work in 30 Days => A's 1 Day work = (1/30)
(A+B) 1 Day work = (1/30 + 1/90)
by solving we get,
A+B 1 Day work = 2/45,
so A and B together can complete work in 45/2 Days.
I think following simple method (alternate) will make you more clear,
A can complete work in N days => A's 1day work = (1/N)----1
B can complete work in n days => B's 1day work = (1/n)----2
Given data,
A thrice as B so , A=3B
A complete work 60 days less than B so, (N=n-60)
Apply in 1 & 2
A's 1day work = (1/(n-60))-----3
B's 1day work = (1/n)--------4
we know that A=3B ; B=(1/n) so,Apply B in A we get[A=3/n]
Apply in 3
3/n=(1/(n-60))
by solving,
3n-180=n
n=90
so, B can complete work in 90 Days => B's 1 Day work =(1/90)
we know that N=n-60,
so, A can complete work in 30 Days => A's 1 Day work = (1/30)
(A+B) 1 Day work = (1/30 + 1/90)
by solving we get,
A+B 1 Day work = 2/45,
so A and B together can complete work in 45/2 Days.
(1)
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