Sally’s parents deposited $15,000 into a college savings account on her third birthday. The account had an interest rate of 9.6% compounded annually. They were hoping that the money would double twice by the time she was 18 years old. Using the rule of 72, t = StartFraction 72 Over r EndFraction will their hopes come true?

a

step-by-step explanation:

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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

i'm sorry i don't know

step-by-step explanation: