Embedly problem 2 in python

embedly2.py

def calcSD(arrVals):
        numVals = len(arrVals)
        print "%d values" % numVals
        total = 0
        for val in arrVals:
                total += val
        mean = total / numVals
        sqDiffs = 0
        for val in arrVals:
                sqDiffs = sqDiffs + (val - mean)**2
        SD = (sqDiffs / numVals)**0.5
        return SD

vals = [4, 5, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 7, 8, 8, 8, 8, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 5, 5, 4, 6, 4]
print calcSD(vals)