Answer and Explanation:
The computation of the evaluation of change in the cost of materials between the two month is given below;
The Cost per unit in September is
= 76,000 ÷ 800
= $95 per unit
And,
Cost per unit in October = $77,350 ÷ 850
= $91 per unit
Now
Cost per unit of materials has been decreased in October by $4 per unit or instead of is by
= (4 ÷ 95 × 100)
= 4.21% .