Question : Mia and Ria can do a piece of work alone in 15 days and 10 days respectively. Mia started the work alone and then after 5 days, Ria joined her till the completion of the work. How long did the work last?
Option 1: 5 days
Option 2: 9 days
Option 3: 12 days
Option 4: 4 days
Correct Answer: 9 days
Solution :
Given: Mia and Ria can do a piece of work alone in 15 days and 10 days, respectively.
Mia in 1 day can do
Ria in 1 day can do
After 5 days Mia can do
So, the remaining part = (
Ria and Mia together in 1 day can do (
They can do
So, they can do
Therefore, the work lasted (5 + 4) = 9 days
Hence, the correct answer is 9 days.
