Question

A and B together can clean a lab in 4 days. A can clean the lab in 20 days.how many days will it take for B to independently complete the task​

Answer 1

Explanation:

it would take 10 times more than that of his mate

Answer 2

Answer:

5 days.

Explanation:

Let the whole work of cleaning lab be 1 .

• A can clean the lab in 20 days

Work done by A = 1/20

• A and B together can clean a lab in 4 days.

Work done by A + B = 1/4

suppose the work is completed by B in x days.

Work done by B = 1/x

Solving these :-

$Work \: done \: by \: A+Work \: done \: by \: B=Work \: done \: by \: (A+B)$

$\frac{1}{20} + \frac{1}{x} = \frac{1}{4}$

$= > \frac{x + 20}{20x} = \frac{1}{4}$

$= > 4x + 80 = 20x$

$= > 20x -4x = 80$

$= > 16x = 80$

$= > x = \frac{80}{16} = 5$

The work is done by B in 5 days.