CAT (QA) PYQs

In an apartment complex, the number of people aged $51$ years and above is $30$ and there are at most $39$ people whose ages are below $51$ years. The average age of all the people in the apartment complex is $38$ years. What is the largest possible average age, in years, of the people whose ages are below $51$ years?

Suppose hospital $A$ admitted $21$ less Covid infected patients than hospital $B$, and all eventually recovered. The sum of recovery days for patients in hospitals $A$ and $B$ were $200$ and $152$, respectively. If the average recovery days for patients admitted in hospital $A$ was $3$ more than the average in hospital $B$ then the number admitted in hospital $A$ was

The average of three integers is $13$. When a natural number $n$ is included, the average of these four integers remains an odd integer. The minimum possible value of $n$ is