Answer:
$311.74
Step-by-step explanation:
A financial calculator computes the payment amount to be $311.74.
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Your graphing calculator may have the capability to do this. Certainly, such calculators are available in spreadsheet programs and on the web.
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The appropriate formula is the one for the sum of terms of a geometric series.
Sn = a1·((1+r)^n -1)/(r) . . . . . where r is the monthly interest rate (0.005) and n is the number of payments (480). Filling in the given numbers, you have ...
$620827.46 = a1·(1.005^480 -1)/.005 = 1991.4907·a1
Then ...
$620827.46/1991.4907 = a1 ≈ $311.74