Question

A can do work in 12 days B can do work in 15 days and C can do work in 20 days in what time can they complete the work together

Answer 1

Answer:

33 days

Step-by-step explanation:

1. A can work 12 day
2. B can work 15 days so 15- 12=3
3. C can work 20 days so 20-12=8
4. so 12+3+8=33 days

Answer 2

Answer:

If A can do a work in 12 days and B can do the work in 15 days and C can do it in 20 days, then A,B and C can together complete the work in 5 days

Step-by-step explanation:

Given

Number of days in which A can do the work = 12 days

Number of days in which B can do the work = 15 days

Number of days in which C can do the work = 20 days

Amount of work A can do in 1 day = $\frac{1}{12} th$ of total work

Amount of work B can do in 1 day = $\frac{1}{15} th$ of total work

Amount of work C can do in 1 day = $\frac{1}{20} th$ of total work

Total amount of work A,B and C can do together in 1 day

$=\frac{1}{12} +\frac{1}{15} +\frac{1}{20} \\\\=\frac{1*5}{12*5} +\frac{1*4}{15*4} +\frac{1*3}{20*3} \\\\=\frac{5}{60} +\frac{4}{60} +\frac{3}{60} \\\\=\frac{12}{60} \\\\=\frac{1}{5}$

Therefore amount of work A,B,and C can together do in a day = $\frac{1}{5}th$ of total work

So, days for completing $\frac{1}{5}th$ of work together = 1 day

days for completing 1 total work together = 1 day *5

= 5 days

Number of days required by A,B and C for completing the work together = 5 days