Question

A and B alone can complete a piece of work in 9 days and 12 days, respectively. In how many days will the work be completed if they work on alternate days starting with A?

• A. $$5\frac13$$
• B. $$11\frac13$$
• C. $$10\frac56$$
• D. $$10\frac14$$

Answer 1

Answer:

$$10\frac14$$

A alone 9 days

B alone 12 days

total work is the LCM of 9 and 12 = 36

one day work of A is 36/9=4

one day work of B is 36/12=3

for alternate work starting A is

4,3,4,3,4,3,4,3,4,3...

after 10 days total work should be 35 work

next day will be A . one day work of A is 4 for one work it is 1/4 days

so the total work days is

$10\frac14$