Question

Compute the missing amount for each of the following notes:

Principal Annual Interest Rate Time Total Interest

(a). $40,000 10% 2.5 years ??

(b). $120,000 ?? 9 months $7,200

(c) ?? 10% 90 days $1,500

(d). $40,000 9% ??   $1,200

Answer 1

a.	$10,000
b.	8%
c.	60,000
d.	4 months

working note:

a.total interest = principal * rate * time

=>40,000 *10% *2.5 years =>$10,000.

b.rate = total interest / (principal * time) *100

=> $7,200 / (120,000 * 9/12 months) *100

=>8%.

c.principal = total interest / (rate*time))

=>1500 / (10%*90 days /360 days)

=>1500/ 0.025

=>$60,000.

d.time = total interest / (principal * rate) * 12 months

=>1200 / (40000*9%) *12 months

=>1200 / 3600 *12 months

=>4 months.