Which of the folldwing is an irrational number?

You can model the population of a certain city between 1955-2000 by the radical function p(x)=55,000 sqrt x-1945. using this model, in which year was the population of that city 220,000

Need on this one asap im almost done with this subject

Divide. write in the simplest form. 4 1/6 divided by 10