It takes 5 hours to fill a container using machine A. The same container can be filled using machine B in 10 hours. When the container is full, Machine C can fully empty the container in 20 hours. If all three machines start working on the same empty container how long will it take for the container to be completely filled,

A 1/2 hours

B 4 hours

C 2 hours

D 15 hours

Solution

Correct Answer: Option B

নল 3টি দ্বারা 1 ঘণ্টায় পূর্ণ হয় = (1/5 + 1/10 − 1/20)
=  (4 + 2 − 1) / 20 অংশ
= 5 / 20 অংশ
= 1/4 অংশ

∴  নল 3টি দ্বারা = 1/4 অংশ পূর্ণ হয় 1 ঘণ্টায়
∴ 1 টি অংশ পূর্ণ হয় (1×4)= 4 ঘণ্টায়

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