To determine the rate of change of this simple index over one week, we need to calculate the total value of the stocks on Day 1 and Day 8, and then find the percentage change between these two values.
### Step-by-Step Solution:
1. Calculate the total value of the stocks on Day 1:
[tex]\[
\text{Total value on Day 1} = (\text{Shares of ABC} \times \text{Price per share of ABC}) + (\text{Shares of XYZ} \times \text{Price per share of XYZ}) + (\text{Shares of QRS} \times \text{Price per share of QRS})
\][/tex]
Substituting the Day 1 values:
[tex]\[
= (8000 \times 4.25) + (5000 \times 2.90) + (2000 \times 6.40)
\][/tex]
[tex]\[
= 34000 + 14500 + 12800 = 61300
\][/tex]
2. Calculate the total value of the stocks on Day 8:
[tex]\[
\text{Total value on Day 8} = (\text{Shares of ABC} \times \text{Price per share of ABC}) + (\text{Shares of XYZ} \times \text{Price per share of XYZ}) + (\text{Shares of QRS} \times \text{Price per share of QRS})
\][/tex]
Substituting the Day 8 values:
[tex]\[
= (8000 \times 3.90) + (5000 \times 2.50) + (2000 \times 6.10)
\][/tex]
[tex]\[
= 31200 + 12500 + 12200 = 55900
\][/tex]
3. Calculate the percentage change in the total value from Day 1 to Day 8:
[tex]\[
\text{Rate of change} = \left( \frac{\text{Total value on Day 8} - \text{Total value on Day 1}}{\text{Total value on Day 1}} \right) \times 100
\][/tex]
Substituting the total values:
[tex]\[
= \left( \frac{55900 - 61300}{61300} \right) \times 100
\][/tex]
[tex]\[
= \left( \frac{-5400}{61300} \right) \times 100
\][/tex]
[tex]\[
= -8.809135399673735
\][/tex]
4. Round the percentage change to the nearest tenth:
[tex]\[
-8.809135399673735 \approx -8.8
\][/tex]
So, the rate of change of the simple index over one week is approximately [tex]\(-8.8\%\)[/tex].
### The correct answer is:
C. [tex]\(-8.4\%\)[/tex]
However, please note that the nearest tenth rounding indicates that:
A. [tex]\(-7.7 \% \)[/tex]
B. [tex]\(7.7 \% \)[/tex]
D. [tex]\( 8.4\%\)[/tex]
are incorrect closest match is:
C. [tex]\(-8.4\%\)[/tex]
The answer by calculations is -8.8%. This represents around -8.8% rather than -8.4% for incremental rounding changes of tenths without mismatched deviations.
Though exact rounding is 10th its marked closest option selection not an equally expected perfect forecast, thus while values closest assumptions it exhibits economic forecast clearly.
