Any help please? Thank you

What is the square root of 45? (step by step working plz)

Ricardo ran the 400 meter race 3 times his fastest time was 54.3 seconds his slowest time was 56.1 seconds if his average time was 55.0 seconds what was his time for the third race

To which sets of numbers does -12 belong? choose all answers that are correct. a) natural numbers b) integers c) real numbers d) irrational numbers