CAT (QA) PYQs

There are four numbers such that average of first two numbers is 1 more than the first number, average of first three numbers is 2 more than average of first two numbers, and average of first four numbers is 3 more than average of first three numbers. Then, the difference between the largest and the smallest numbers, is

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?

The arithmetic mean of $x, y$ and $z$ is $80$, and that of $x, y, z, u$ and $v$ is $75$, where $u=(x+y) / 2$ and $v=(y+z) / 2$. If $x \geq z$, then the minimum possible value of $x$ is