Answer:
$0.025x² . . . where x is a number of percentage points
Explanation:
The multiplier for semi-annual compounding will be ...
(1 + x/2)² = 1 + x + x²/4
The multiplier for annual compounding will be ...
1 + x
The multiplier for semiannual compounding is greater by ...
(1 + x + x²/4) - (1 + x) = x²/4
Maria's interest will be greater by $1000×(x²/4) = $250x², where x is a decimal fraction.
If x is a percent value, as in x = 6 when x percent = 6%, then the difference amount is ...
$250·(x/100)² = $0.025x² . . . where x is a number of percentage points
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Example:
For x percent = 6%, the difference in interest earned on $1000 for one year is $0.025×6² = $0.90.