Joy Shaha wrote:Q. 12 children take 16 days to complete the work which can be completed by 8 adults in 12 days.16 adults started work and after 3 days 10 adults left & 4 children join them.How many days will they take to complete the work.
A.3;
B.4;
C.6;
D.8;
E.None
Let the job = 96 units.
12 children take 16 days:
Work produced each day = (total job)/(number of days) = 96/16 = 6 units per day.
Thus, the daily rate for each child = (total work per day)/(number of children) = 6/12 = 1/2 unit per day.
8 adults take 12 days:
Work produced each day = (total job)/(number of days) = 96/12 = 8 units per day.
Thus, the daily rate for each adult = (total work per day)/(number of adults) = 8/8 = 1 unit per day.
For the first 3 days, 16 adults work:
Since each adult produces 1 unit per day, the daily rate for 16 adults = 16 units per day.
At a rate of 16 units per day, the amount of work produced over 3 days = rt = 16*3 = 48 units.
Remaining units = 96-48 = 48 units.
After 3 days 10 adults left & 4 children join them:
After 10 adults leave, the daily rate for the remaining 6 adults = 6 units per day.
Since each child produces 1/2 unit per day, the daily rate for 4 children = 2 units per day.
Combined rate for 6 adults and 4 children = 6+2 = 8 units per day.
At a combined rate of 8 units per day, the time to produce the remaining 48 units = w/r = 48/8 = 6 days.
The correct answer is
C.
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