Question

4.
A can build a wall in 20 days, B can build it in 25
days, C aan destroy the complete wall in 40 days.
They start work on alternate days in such a way
that, A start the work, followed by B next day,
then by C next day, then A next day and so on.
How many days will it take to complete the wall if
it's given that once the wall has been made, none
of A, B and C work on the wall?

Answer 1

Answer:

It's 44 days

Step-by-step explanation:

Answer 2

The wall will be built in 47 days or 46 days with some extra hours.

Number of days A takes to build the wall $=20\ days$

Number of days B takes to build the wall $=25\ days$

Number of days C takes to destroy the wall $=40\ days$

According to the information given in the question,

let the time taken to build the wall once will be x days.

A, B, and  C are working alternatively till the wall is done once.

$(\frac{1}{20}+ \frac{1}{25}- \frac{1}{40})=\frac{13}{200}$

Hence the one unit of work can be done in 3 days as they are working alternatively, so,

one day's work done by all three will be $\frac{13}{200}\times \frac{1}{3}=\frac{13}{600}$.

Therefore the work will be completed in $\frac{600}{13}=46.15 \ days$.

Or we can say the wall will be built in 47 days or 46 days with some extra hours.

#SPJ2