QA – Placement Quizzes | Work and Wages | Question 6
A person employed a group of 20 men for a construction job. These 20 men working 8 hours a day can complete the job in 28 days. The work started on time but after 18 days, it was observed that two thirds of the work was still pending. To avoid penalty and complete the work on time, the employer had to employ more men and also increase the working hours to 9 hours a day. Find the additional number of men employed if the efficiency of all men is same.
Explanation: Let the total work be 3 units and additional men employed after 18 days be ‘x’.
=> Work done in first 18 days by 20 men working 8 hours a day = (1/3) x 3 = 1 unit
=> Work done in last 10 days by (20 + x) men working 9 hours a day = (2/3) x 3 = 2 unit
Here, we need to apply the formula M1 D1 H1 E1 / W1 = M2 D2 H2 E2 / W2, where
M1 = 20 men
D1 = 18 days
H1 = 8 hours/day
W1 = 1 unit
E1 = E2 = Efficiency of each man
M2 = (20 + x) men
D2 = 10 days
H2 = 9 hours/day
W2 = 2 unit
So, we have
20 x 18 x 8 / 1 = (20 + x) x 10 x 9 / 2
=> x + 20 = 64
=> x = 44
Therefore, additional men employed = 44
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