Answer:
$1,892.8
Step-by-step explanation:
Variable cost per minute:
= Change in cost ÷ Change in minute
= (4,000 - $2,640) ÷ (480 - 170)
= 1,360 ÷ 310
= 4.39 per minute
Fixed cost:
= January total bill - (January minutes × Variable cost per minute
= 4,000 - (480 × 4.39)
= 4,000 - 2,107.2
= $1,892.8
Therefore, the fixed portion of the total cost is $1,892.8