Answer:
<em>Student 2 is incorrect because he didn't use the formula properly</em>
Step-by-step explanation:
The exponential function is often used to model natural growing or decaying processes, where the change is proportional to the actual quantity.
An exponential decaying function is expressed as:

Where:
C(t) is the actual value of the function at time t
Co is the initial value of C at t=0
r is the decaying rate, expressed in decimal
The initial value of the item is Co=$1000, the rate of decay is r=40%=0.4, and the time is t=3 years.
Substituting into the formula:


C(3)=$216
Student 2 is incorrect because he didn't use the formula properly
Mean, in terms of math, is the total added values of all the data in a set divided by the number of data <em>in</em> the set. Make sense? If not, here' an example...
Let's say this is my data set:
1, 2, 5, 4, 3, 8, 7, 4, 6,10
To find the mean...
Step 1: Add all of them together.
1+2+5+4+3+8+7+4+6+10 is what? 50. Now that you have this number...
Step 2: Divide by the amount there are. Basically, count up all of the numbers. How many are there? There are 10. Finally...
Step 3: Divide. 50/10 is 5, so the mean of this data set would be 5. Get it? I sure hoped this helped :)
A. Put parenthesis around 12-3. This will reduce the amount you are dividing 6*5 by and give you the highest possible answer.
B. Put parenthesis around 3+4. This will simplify into 7*7, giving you the correct answer, 49.
Hope this helps!