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:
15 days
20 days
25 days
30 days
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 4 of 15.

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?

Guru said:   2 decades ago
Thank you Nagu i get an idea from your explaination.

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.

Nitesh Nandwana said:   1 decade ago
@Awoke

Your method is best out of all explanation. Good job, keep it up.

Kinnari said:   1 decade ago
I like your method Mr. Awoke. :)

Nishant said:   1 decade ago
LET B+C CAN FINISH WORK IN T DAYS
THEN B+C'S 1 day work=1/T.
then,
A's 1 day work=1/T.
so,
B+C's 1 day work=1/T.
now,(A + B)'s 1 day's work =1/10.
then B's 1 day work=1/10-1/T.--------(1)
and C's 1 day's work =1/50.
hence,B's 1 day work=i/T-1/50.-------(2)
now,
from (1) nd (2)
T = 25 days.
then B=50 days.

how it is possible????

Aunjani Kumar said:   1 decade ago
From (i) and (ii), we get: 2 x (A's 1 day's work) = 3/25

Dear i am not able to understand why 2 multiplied with A's day's work??????

Hilal said:   1 decade ago
B's work=x
C's work=y
hence A's work=x+y
A and B together work= 2x+y
given y=1/50
substituting x=1/25


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