The mean absolute deviation (MAD) and the BIAS are found to be

Question

A dealer for washing machines forecasts the demand at the rate of 600 units per month, for the next four months. The actual demand is found to be 500, 680, 800 and 900 units. The mean absolute deviation (MAD) and the BIAS are found to be                                                        

(a) 170 and –120            (b) –120 and 170

(c) 340 and –240            (d) –240 and 340