If 3 men or 4 women can plow a field in 43 days, how long will 7 men and 5 women take to plow it?
A. 12 days
B. 10 days
C. 15 days
D. 8 days
Answer: Option A
Solution (By JKExamLibrary)
3 Men = 4 Women => 1 Man = 4/3 Women. 7 men + 5 women = 7 * (4/3) + 5 = 28/3 + 5 = 43/3 women. Since 4 women take 43 days, 43/3 women will take (4 * 43) / (43/3) = 4 * 3 = 12 days.
A, B and C can complete a piece of work in 10, 12 and 15 days respectively. They started together but A left 2 days after the start and B left 3 days before the completion of the work. How long did the work last?
Explanation:
Total work = LCM(10, 12, 15) = 60 units. Efficiency of A = 6, B = 5, C = 4. Let total days be x. A works for 2 days. B works for (x - 3) days. C works for x days. Total work = 2*6 + (x - 3)*5 + 4*x = 60 => 12 + 5x - 15 + 4x = 60 => 9x - 3 = 60 => 9x = 63 => x = 7 days.
A, B and C can do a piece of work in 24, 30 and 40 days respectively. They start together but C leaves 4 days before the completion of the work. In how many days was the work completed?
Explanation:
Total work = LCM(24, 30, 40) = 120 units. Efficiency of A = 5, B = 4, C = 3. Let the total number of days be x. A and B work for x days, while C works for (x - 4) days. 5x + 4x + 3(x - 4) = 120 => 12x - 12 = 120 => 12x = 132 => x = 11 days.
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