Multiple choice

$150$ workers were engaged to finish a piece of work in a certain number of days. $4$ workers dropped the second day, $4$ more workers dropped the third day and so on. It takes eight more days to finish the work now. The number of days in which the work was completed is

  1. $15$
  2. $20$
  3. $25$
  4. $30$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the original days be D. Total work = 150 * D. With the reduction, work = 150 + 146 + 142 + ... for (D+8) days. Solving the arithmetic progression sum for D yields D = 17, so total days = 17 + 8 = 25.

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