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3 boys can do a piece of work in 18 days. 6 girls can do the same piece of work in 18 days. In how many days, 4 boys and 4 girls together will finish the work?
3 boys can do a piece of work in 18 days. 6 girls can do the same piece of work in 18 days. In how many days, 4 boys and 4 girls together will finish the work?
1).
6 days
2).
12 days
3).
8 days
4).
9 days
1 answers
1 vote
We know that formula:
If M1 persons can do W1 work in D1 days working T1 hours per day and M2 persons can do W2 work in D2 days working T2 hours per day, then the relationship between them is:
M1 × D 1 × T1 × W2 = M2 × D 2 × T2 × W1
Now,
3B × 18 = 6G × 18
⇒ 3B = 6G
⇒ B = 2G
Now, according to the question:
Let the 4 boys and 4 girls would take ‘x’ days to complete the same work:
3B × 18 = (4B + 4G) × x
⇒ 3 × 2G × 18 = (4 × 2G + 4G) × x
⇒ 6G × 18 = 12G × x
⇒ x = 9
∴ The required number of days is 9.