Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 8)
8.
A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in:
Answer: Option
Explanation:
| (A + B)'s 1 day's work = | 1 |
| 10 |
| C's 1 day's work = | 1 |
| 50 |
| (A + B + C)'s 1 day's work = |  |
1 | + | 1 |  |
= | 6 | = | 3 | . .... (i) |
| 10 | 50 | 50 | 25 |
A's 1 day's work = (B + C)'s 1 day's work .... (ii)
| From (i) and (ii), we get: 2 x (A's 1 day's work) = | 3 |
| 25 |
 A's 1 day's work = |
3 | . |
| 50 |
 B's 1 day's work |
|
1 | - | 3 | |
= | 2 | = | 1 | . |
| 10 | 50 | 50 | 25 |
So, B alone could do the work in 25 days.
Discussion:
146 comments Page 1 of 15.
Priyanka said:
2 decades ago
I'm not getting how 2*(a`s 1day work)=3/25
Suganya said:
2 decades ago
How you get that 2*(A's 1day work)=3/25
Vinoth said:
2 decades ago
How u got x (A's 1 day's work) = 3/25
Ankit purwar said:
2 decades ago
How u get x= 3/25?
Nagu said:
2 decades ago
Hi Guys,
In this problem
A's one day work is equal to (b+c)'s one day work
A = (B+C)
So a+b+c become 2A here they taken instead of b+c= a
so A+B+C = A+ (B+C) = A+A becasue B+C=A
3/25 = 2* (A's one day work)
so 2* A's one day work
I THINK YOU ALL UNDER STOOD THE TRICK..
In this problem
A's one day work is equal to (b+c)'s one day work
A = (B+C)
So a+b+c become 2A here they taken instead of b+c= a
so A+B+C = A+ (B+C) = A+A becasue B+C=A
3/25 = 2* (A's one day work)
so 2* A's one day work
I THINK YOU ALL UNDER STOOD THE TRICK..
(1)
Guru said:
2 decades ago
Thank you Nagu i get an idea from your explaination.
Awoke said:
2 decades ago
Short cut method:
A + B = 1/10 but A = B + C, then
A + B = B + B + C = 1/10 and C = 1/50
2B + 1/50 = 1/10 gives us
B = 1/2(1/10-1/50)
= 1/2(2/25)
= 1/25
Therefore, B can do the work alone in 25 days.
A + B = 1/10 but A = B + C, then
A + B = B + B + C = 1/10 and C = 1/50
2B + 1/50 = 1/10 gives us
B = 1/2(1/10-1/50)
= 1/2(2/25)
= 1/25
Therefore, B can do the work alone in 25 days.
(1)
Sneha said:
2 decades ago
We can explain much easier than this:
Here we know A = B + C
So in the equation A + B + C = 3/25, substitute B + C for A.
We get 2(B + C) = 3/25 --->2A
Hence A's 1 day work is = 3/25*2 = 3/50
Then do the remaining part and find work done by B.
Here we know A = B + C
So in the equation A + B + C = 3/25, substitute B + C for A.
We get 2(B + C) = 3/25 --->2A
Hence A's 1 day work is = 3/25*2 = 3/50
Then do the remaining part and find work done by B.
Nitesh Nandwana said:
1 decade ago
@Awoke
Your method is best out of all explanation. Good job, keep it up.
Your method is best out of all explanation. Good job, keep it up.
Kinnari said:
1 decade ago
I like your method Mr. Awoke. :)
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