15,500 for 7.5 years at 4.2% annual compound interest. Find the interest earned:

$4882.50

Step-by-step explanation:

First, converting R percent to r a decimal

r = R/100 = 4.2%/100 = 0.042 per year,

then, solving our equation

I = 15500 × 0.042 × 7.5 = 4882.5

I = $ 4,882.50

The simple interest accumulated

on a principal of $ 15,500.00

at a rate of 4.2% per year

for 7.5 years is $ 4,882.50.

$5602.78

Step-by-step explanation:

For for compound interest is A = P(1 + r/n)^(nt)  where A is the new total, P is the amound invested, t is the number of years, r is the rate of interest and n is the number of times each year the interest is figured.  In your problem, P = 15500, r = .042, n = 1. t = 7.5.  So, substituting in we get

A = 15500(1+.042/1)^7.5(1)

A = 15500(1.36146...) = 21102.78

Therefore the interest earned is 21102.78-15500 = 5602.78

b

step-by-step explanation: