Question

a can do a job in 20 days,b in 30 days and c in 60 days.If b and c, help a on the third day, how long will that work be completed?​

Answer 1

Answer:

The work will be completed in 15 days.

Step-by-step explanation:

Consider the provided information.

We are given that A can do a job in 20 days, B in 30 days and C in 60 days and If B and C, help A on the third day, how long will that work be completed?

A works for 1 day and finishes $\frac{1}{20}$th of work, B works for 1 day and finishes $\frac{1}{30}$th of work and C works for 1 day and finishes $\frac{1}{60}$th of work.

The first two days A works alone. So,  

On the first day = $\frac{1}{20}$th of work.

On the second day = $\frac{1}{20}$th of wok.

And on the third day = $\frac{1}{20} + \frac{1}{30} + \frac{1}{60} = \frac{1}{10}$th of work.

In 3 days, $\frac{1}{10} + \frac{1}{10} = \frac{1}{5}$th of work is done.

So the work will complete in $5 \times 3 = 15$ days.

Therefore, The work will be completed in 15 days.

Answer 2

Solution,

• Work done by A in 1 days = 1/20

• Work done by B in 1 days = 1/30

• Work done by C in 1 days = 1/60

The first two days A works alone.

1. 1st day = 1/20

2. 2nd day = 1/20

3. 3rd day

=

$\boxed{ \rm \bold{ : \to \: \frac{1}{20} + \frac{1}{30} + \frac{1}{60} = \frac{1}{10} }} \\ \\ \rm \bold{ : \to \: in \: \: 3days \: \frac{1}{10} + \frac{1}{20} + \frac{1}{20} } \\ \\ : \to \rm \bold{ \frac{1}{5} } \: work \: in \: done. \\ \\ \rm : \to \bold{the \: \: whole \: \: work \: \: is \: \: done \: \: 15 \: \: days.}$