A can complete a piece of work in 4 days; B takes double the time take...
Amounts of work done in one day by A, B, C and D are 1/4, 1/8, 1/16, and 1/32, respectively.
Using options, we note that the pair of B and C does 3/16 of work in one day.
The pair of A and D does
of the work in one day.
Hence, A and D take 32/9 days.
A can complete a piece of work in 4 days; B takes double the time take...
Given:
A can complete the work in 4 days.
B takes double the time taken by A.
C takes double the time taken by B.
D takes double the time taken by C.
Let's find the time taken by each person to complete the work:
A takes 4 days.
B takes double the time taken by A, so B takes 2 * 4 = 8 days.
C takes double the time taken by B, so C takes 2 * 8 = 16 days.
D takes double the time taken by C, so D takes 2 * 16 = 32 days.
Now, let's consider the pairs of workers:
The first pair takes two-thirds of the time taken by the second pair to complete the work.
Let's assume the first pair completes the work in X days.
So, the second pair will take (2/3)X days to complete the work.
Now, let's calculate the time taken by the first pair:
A takes 4 days, and B takes 8 days. So, together, A and B can complete the work in 4 * 8 / (4 + 8) = 32 / 12 = 8/3 days.
Similarly, let's calculate the time taken by the second pair:
C takes 16 days, and D takes 32 days. So, together, C and D can complete the work in 16 * 32 / (16 + 32) = 512 / 48 = 32/3 days.
According to the given condition, the first pair takes two-thirds of the time taken by the second pair to complete the work. So, X = (2/3) * (32/3) = 64/9 days.
Therefore, the first pair consists of A and D, as they are the only pair that can complete the work in 64/9 days.
Hence, the correct answer is option D) A and D.