Answer: the ordinary interest is $6.5625
Explanation:
In calculating ordinary interest, the number of days in a month is considered to be 360 days. We would apply the formula for determining simple interest which is expressed as
I = PRT/100
Where
I represents interest paid on the loan.
P represents the principal or amount taken as loan
R represents interest rate
T represents the duration of the loan in years.
From the information given,
P = $420
R = 6.25%
T = 90 days = 90/360 = 0.25 day
I = (420 × 6.25 × 0.25)/100
= $6.5625