switch, menu functions

so one of the hw problems i'm working on has thrown me into a big puzzle, i'm not sure whats going on. the question ask you to imprt a text file (which i did ) which are grades for few students for a quiz and 3 exams. it says that make a function to determine what a student needs to make in the final in order to have an A B C D in class. It says give the user a menu to ask them what grade they want, depending on there choice use switch function to determine what function to use

here's what i have so far

(function)

function [ finalA ] = grades_finalA( q1,e1, e2, e3 )

finalA=(90-q1*.10-e1*.20-e2*.20-e3*.20)/.30;

end

function [ finalB ] = grades_finalB( q1,e1, e2, e3 )
finalB=(80-q1*.10-e1*.20-e2*.20-e3*.20)/.30;
end 

function [ finalC ] = grades_finalC( q1,e1, e2, e3 )
finalC=(70-q1*.10-e1*.20-e2*.20-e3*.20)/.30;
end

function [ finalD ] = grades_finalD( q1,e1, e2, e3 )
finalD=(60-q1*.10-e1*.20-e2*.20-e3*.20)/.30;
end

%%script 

clc 
clear all 
load grades2.txt
grades2(:,2)=q1;
grades2(:,3)=e1;
grades2(:,4)=e2;
grades2(:,5)=e3;
pick=menu('Grades','A','B','C','D')
grades2(:,2)=q1;
grades2(:,3)=e1;
grades2(:,4)=e2;
grades2(:,5)=e3;
switch pick
    case 1
        final=grades_finalA(q1,e1,e2,e3)
    case 2
        final=grades_finalB(q1,e1,e2,e3)
    case 3
        final=grades_finalB(q1,e1,e2,e3)
    case 4
        final=grades_finalB(q1,e1,e2,e3)
end