Question

142. Twenty five workers were employed to complete
a compound wall in 12 days. Five workers left
after working for 4 days. The remaining 20
workers completed the work. In how many
days the total job was completed?
(a) 15 days
(b) 16 days
(c) 14 days
(d) 18 days.
143. In a garden there are 8 rows and 10 columne
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Answer 1

14 Days.

If 1 worker was to make the wall then he would take 25×12 days. So 300 Days.

25 workers worked for 4 days. They did the same work which a single worker would have done in 100 days. So 200 Days of work is left. 20 workers would do the work in 200/20 days= 10 days. So total days =10+4=14 days.

Answer 2

Given :

Twenty five workers were employed to complete  a compound wall in 12 days. Five workers left  after working for 4 days. The remaining 20  workers completed the work.

To Find:

In how many  days the total job was completed?

Solution:

25 workers completed work in days = 12

25 workers 1 day work =$\frac{1}{12}$

25 workers 4 days work = $\frac{4}{12}$

Remaining work =$1-\frac{4}{12}=\frac{8}{12}$

25 workers complete work in days = 12

1 worker complete work in days =$12 \times 25$

20 workers complete work in days = $\frac{12 \times 25}{20}$

20 workers complete$\frac{8}{12}$work in days = $\frac{12 \times 25}{20} \times \frac{8}{12}=10$

No. of days required to complete work = 10+4=14 days

Hence the total job was completed in 14 days