Help please!! I'm really struggling with these

At oaknoll school, 90 out of 270 students on computers. what percent of students at oak knoll school do not own computers? round the nearest tenth of a percent.

How can you find the magnitude of a vector, v = < x,y > , where the horizontal change is x and the vertical change is y?

Q= {1.7, 1.1, 1.4, 2.1, 2.3, s}. what is the absolute difference between the greatest and least possible values of the median of set q? express your answer as a decimal to the nearest hundredth.