8 men working for 9 hours a day complete a piece of work in 20 days. In how many days can 7 men working for 10 hours a day complete the same piece of work?
Answer
Answer (as printed):
Explanation
Let the required number of days be x. Less men, More days (Indirect Proportion) More hours per day, Less days (Indirect Proportion) Men 7:8 :: 20 : x Hours per day 10 : 9 8 × 9 × 20 144 4 \ (7 × 10 × x) = (8 × 9 × 20) ⇔ x = 7 × 10 = 7 = 20 7 . Hence, required number of days = 20 4 . 7
Explanation as extracted from the printed page; notation may be imperfect.