If A, B and C can do a task working alone in 12, 18 and 36 days respectively. They all work together for 2 days, then B quits. How many days A and C working together will take to complete the remainder of the task?
If A, B and C can do a task working alone in 12, 18 and 36 days respectively. They all work together for 2 days, then B quits. How many days A and C working together will take to complete the remainder of the task? Correct Answer 6
A can do a task in = 12 day
∴ A’s 1 day’s task = 1/12
B can do a task in = 18 day
∴ B’s 1 day’s task = 1/18
C can do a task in = 36 day
∴ C’s 1 day’s task = 1/36
Let, A and C will take x days to complete the remainder of the task
According to the question,
⇒ (x + 2) × 1/12 + 2/18 + (x + 2) × 1/36 = 1
⇒ x/12 + 1/6 + 1/9 + x/36 + 1/18 = 1
⇒ (3x + x)/36 = 1 - (3 + 2 + 1)/18
⇒ x/9 = 1 - 1/3
⇒ x/9 = 2/3
⇒ x = 6
∴ A and C will take 6 days to complete the remainder of the task.
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Feb 20, 2025