5.) $28,000 invested at a rate of 4% compounded annually a.) Write a compound interest function to model the situation.

ok so we know the amount we know the interest amount but we do know know the period of time so the equation would look like this

28000(0.4)T=I

T=Time

I=interest

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

make sure you have version 2.50

try looking in the very back of the book : )

step-by-step explanation:

you can download it here