You are given the following budgeted and actual data for the Grey Company for each of the months January through June of the current year.

In December of the prior year, sales were forecasted as follows: January, 100 units; February, 95 units; March, 100 units; April, 110 units; May, 120 units; June, 125 units. In January of the current year, sales for the months February through June were reforecasted as follows: February, 90 units; March, 100 units; April, 105 units; May, 110 units; June, 120 units. In February of the current year, sales for the months March through June were reforecasted as follows: March, 95 units; April, 105 units; May, 105 units; June, 120 units. In March of the current year, sales for the months April through June were reforecasted as follows: April, 105 units; May, 100 units; June, 110 units. In April of the current year, sales for the months May and June were reforecasted as follows: May, 90 units; June, 105 units. In May of the current year, sales for June were reforecasted as 105 units.

Actual sales for the six-month period were as follows: January, 98 units; February, 95 units; March, 92 units; April, 108 units; May, 98 units; June, 100 units.

Required

1. For each of the months January through June, inclusive, prepare a rolling forecast of sales volume.

2. For each of the months March through June, determine the three-month forecast error rate, defined as 1 minus the absolute percentage error. For example, the forecast error rate for March's sales is found by dividing the absolute value of the forecast error for this month by the actual sales volume for the month. The forecast error for any month (e.g., March) is defined as the difference between the actual sales volume for the month and the sales volume for that month forecasted three months earlier (e.g., December).