CAT (QA) PYQs

A person can complete a job in $120$ days. He works alone on Day $1$. On Day $2$, he is joined by another person who also can complete the job in exactly $120$ days. On Day $3$, they are joined by another person of equal efficiency. Like this, everyday a new person with the same efficiency joins the work. How many days are required to complete the job?

Gautam and Suhani, working together, can finish a job in $20$ days. If Gautam does only $60 \%$ of his usual work on a day, Suhani must do $150 \%$ of her usual work on that day to exactly make up for it. Then, the number of days required by the faster worker to complete the job working alone is

Anil can paint a house in $12$ days while Barun can paint it in $16$ days. Anil, Barun, and Chandu undertake to paint the house for ₹ $24000$ and the three of them together complete the painting in $6$ days. If Chandu is paid in proportion to the work done by him, then the amount in INR received by him is