Required information

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Jorgansen Lighting, Incorporated, manufactures heavy$-$duty street lighting systems for municipalities. The company uses

variable costing for internal management reports and absorption costing for external reports. The company provided the

following data:

The company's fixed manufacturing overhead per unit was constant at $$570$ for all three years.

Assume in Year $4$ the company's variable costing net operating income was $$250,000$ and its absorption costing net operating

income was $$300,000.$

a$.$ Did inventories increase or decrease during Year $4?$

b$.$ How much fixed manufacturing overhead cost was deferred or released from inventory during Year $4?$