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Doctors Medicines MCQs Q&A

  1. 5 hrs
  2. 7 hrs
  3. 6 hrs
  4. 3 hrs
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1 Answers

Option 3 : 6 hrs

Let A and B together complete the work in "t" hours

Now, according to question

Work done by A

t + + 4.5 = (t + 4.5)/A

t/A = 4.5/B

A/B = t/4.5      ----(1)

Similarly work done by B,

t + + 8 = (t + 8)/B

t/B = 8/A

A/B = 8/t      ----(2)

Comparing (1) and (2), we get

t/4.5 = 8/t

t2 = 36

∴ t = 6 hours

∴ A and B will together complete the task in 6 hours

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