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CAT 2001 — QA Question 9

BasicsEasy

A can complete a piece of work in 4 days. B takes double the time taken by A, C takes double that of B, and D takes double that of C to complete the same task. They are paired in groups of two each. One pair takes two thirds the time needed by the second pair to complete the work. Which is the first pair?

Answer & solution

  • A

    A, B

  • B

    A, C

  • C

    B, C

  • A, D

Solution

If A takes 4 days then, B will take 8 days, C will take 16 days and D will take 32 days.

∴ Time taken by A and B together to complete a work =(4×8)8+4=83 days

∴ Time taken by A and C together to complete a work =(4×16)16+4=165 days

∴ Time taken by A and D together to complete a work =(4×32)32+4=329 days

∴ Time taken by A and C together to complete a work =(8×16)8+16=163 days

∴329=23×163

∴ The pairs are (A, D) and (B, C).

Hence, option (d).

CAT 2001 QA Q9: A can complete a piece of work in 4 days. B takes double the time taken by A, C takes double that of B, and D — Solution | TheCATExam