name = "Jack"
gpaList = [3.5,4,3.94,4,4,4,4]


def gpa(name, gpaList):
    sumgpa = 0
    for i in range(len(gpaList)):
        sumgpa = sumgpa+float(gpaList[i])
    
    print "%s's overall average GPA is %s" % (name ,str(sumgpa/len(gpaList)))
    

def gpaK(name, gpaList, k):
    if k>0 and k<=len(gpaList):
        sumgpa = 0
        for i in range(len(gpaList)- k, len(gpaList)):
            sumgpa = sumgpa+float(gpaList[i])
        
        print "%s's overall average GPA is " % name  + str(sumgpa/k)
    else:
        print "Please input k in range of your list's length."
gpa(name,gpaList)

gpaK(name, gpaList, 4)