# Quiz - Extras 2ΒΆ

A primary school is planning a field trip to the zoo for some of its students. For this, the school can only spend exactly `budget` units. It is known that the entry to the zoo costs 5 units for children under 12 years old and 7 units for those who are 12 years old or older. Develop the function `maximo_estudiantes` that receives `budget`, a positive integer that indicates the budget that the school intends to spend. The function should return a tuple `(p, g)` with the maximum number of small and large students that the school can take to the zoo considering all values as integers.

Develop the function `a_romano`, which receives a positive integer `n` greater than zero. The function should return the conversion of the number from Arabic to Roman numerals. The function should return a string that represents the number in Roman numerals.

Examples:
`a_romano(5)` -> `"V"`
`a_romano(10)` -> `"X"`
`a_romano(25)` -> `"XXV"`
`a_romano(2011)` -> `"MMXI"`

Develop the function `calcular_pi`, which receives a positive parameter `n` greater than 0. The function should calculate the approximate value of `pi` with `n` terms, according to the following formula.

`pi = (4/1) - (4/3) + (4/5) - (4/7) ...`

The result should be rounded to 2 decimals and returned as a string.

Examples:
`calcular_pi(4)` -> `"2.90"`
Explanation: The first 4 terms following the formula are: `(4/1) - (4/3) + (4/5) - (4/7)` which result in `2.895238095`, rounding to two decimal places the final result would be `2.90`
`calcular_pi(24)` -> `"3.10"`
`calcular_pi(61)` -> `"3.16"`
`calcular_pi(100)` -> `"3.13"`