Question

The value, V, of Kalani’s stock investments over a time period, x, can be determined using the equation v=750(0.80)-x. What is the rate of increase or decrease associated with this account? 20% decrease 20% increase 25% decrease 25% increase

Answer 1

The rate of increase and decrease associated with Kalani's stock investments would be a 25% per year increase.

Therefore, the correct option of all the answer choices you listed is: C.

Answer 2

Answer:

Hence, the rate of change is:

25% increase.

Step-by-step explanation:

We are given a function V, of Kalani's stock investments over a time period,x as:

$V(x)=750\times (0.80)^{-x}$

Now the rate of increase or decrease in percent associated with this account can be calculated as:

$\dfrac{V(x+1)-V(x)}{V(x)}\times 100$

$=\dfrac{750\times (0.80)^{-(x+1)}-750\times (0.80)^{-x}}{750\times (0.80)^{-x}}\times 100\\\\\\=\dfrac{750\times (0.80)^{-x}\times ((0.80)^{-1}-1)}{750\times (0.80)^{-x}}\times 100\\\\\\\\=(\dfrac{1}{0.80}-1)\times 100\\\\=\dfrac{1-0.80}{0.80}\times 100\\\\\\=\dfrac{0.20}{0.80}\times 100\\\\=\dfrac{20}{80}\times 100\\\\=\dfrac{1}{4}\times 100\\\\=25\%$

Hence, the rate of increase is:

25%.