alleryA is twice as efficient as B. B alone finishes a job in 18 days. How long do A and B together take?
A$12$ days
B$6$ days
C$9$ days
D$4.5$ days
Answer & Solution
Correct answer: B. $6$ days
B's rate = 1/18. A is twice as efficient: A's rate = 2/18 = 1/9. Combined = 1/9 + 1/18 = 2/18 + 1/18 = 3/18 = 1/6. Time = 6 days.
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