Pouring concrete

Algebra Level 2

Several construction workers are laying a foundation. Every day they pour in the same amount of concrete that is in the foundation already. For example, if there are three units of concrete on day one, then the workers will add three more units of concrete the next day making six. The next day, they will add six to make a total of twelve and so on. If it takes 88 days to fill the entire foundation with concrete, how many days does it take to fill one-eighth of the foundation?


The answer is 85.

Nature Lover by Nature Lover , 31, USA

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1 solution

Zee Ell
Aug 15, 2016

The amount of concrete doubles each day, which means that the total amount of concrete was the half on the previous day.

Therefore, at the end of the:

  • 87th day the foundation was 1 2 \frac {1}{2} full

  • 86th day the foundation was 1 4 \frac {1}{4} full

  • 85th day the foundation was 1 8 \frac {1}{8} full

Therefore, our answer should be: 85 \boxed {85}

1 Helpful 0 Interesting 0 Brilliant 0 Confused

Yes correct

Nature Lover - 4 years, 10 months ago

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