Multiple choice

$45$ men working $8$ hours a day can finish a project within a given time. Five men are unable to report for the work. How long should the rest work a day to finish the project on time.

  1. $\;10\:hrs$
  2. $\;12\:hrs$
  3. $\;9\:hrs$
  4. $\;8\:hrs$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the man-hour principle (M1*D1*H1 = M2*D2*H2), we have 45 * T * 8 = 40 * T * H2. Solving for H2 gives H2 = (45 * 8) / 40 = 9 hours.

AI explanation

Using the formula for constant man-hours, $M_1 \times H_1 = M_2 \times H_2$, we have $45 \times 8 = 40 \times H_2$. This gives $360 = 40 \times H_2$, so the remaining men must work 9 hours a day.

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