The actual forecasted demand (in units) for product in 11 periods are: Actual: 422, 444, 417, 396, 442, 417, 422, 450, 379, 420, 471 Forecast: 399, 417, 438, 422, 402, 433, 421, 422, 444, 394, 414 having trouble finding the value of the mean squared error