Engineering Maths - Time and Work

Refer to the data below and answer the questions that follow.
The boiler tank in a chemical factory holds 105 litres. 5 tanks each having one-fifth the capacity of the boiler tank fill in ‘hard water’ at same rates in the boiler tank in 2 hours. The outlet of the two of smaller tanks work as inlet pipes and other two work as outlet and the fifth tank fill in the main ‘boiler’ at half its efficiency.

9. What is the number of hours taken to fill in the main boiler when all the pipes are opened at once?

  • Option : C
  • Explanation :
    Since 5 tanks of same efficiency fill the boiler in 2 hours each tank individually takes
    2 x 5 = 10 hours to fill it.
    Tank with half the efficiency will take 10 x 2 = 20 hours.
    In one hour, fraction of boiler getting filled when 4 fully efficient pipes with two as inlet and two as outlet and 5th acts at 50% efficiency as an inlet is

    Hence it will take 20 hours to fill the boiler tank.
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Refer to the data below and answer the questions that follow.
The boiler tank in a chemical factory holds 105; litres. 5 tanks each having one-fifth the capacity of the boiler tank fill in ‘hard water’ at same rates in the boiler tank in 2 hours. The outlet of the two of smaller tanks work as inlet pipes and other two work as outlet and the fifth tank fill in the main ‘boiler’ at half its efficiency.