A sample of a radioactive isotope had an initial mass of 370 mg in the year 2007 and decays exponentially over time. A measurement in the year 2012 found that the
sample's mass had decayed to 80 mg. What would be the expected mass of the
sample in the year 2020, to the nearest whole number?

the answer is c 150

step-by-step explanation:

113.42

i hope that is right.

step-by-step explanation:

unless you made a typo, the answers are both a and c.

step-by-step explanation:

1.5/3 is .5 whereas 3/9 is .3333333 not proportional

22/33 is .66666 and 4/6 is also .66666 proportional

2/4 is .5 whereas 142/213 is .66666 not proportional

14/7 is 2 and 7/3.5 is also 2 proportional

you could've also checked it by doing this simple division:

if the larger fraction divides with the smaller fraction to equal 1, it is proportional. so let me show you what i mean:

when i divide 22/33 by 4/6 i get 1, so we know it is proportional, and it is the same with 14/7 and 7/3.5. now if i divide 3/9 by 1.5/3 i get .66666 so therefore we know it is not proportional.

there are many ways to do this so i wanted to show you some possible ways.