Calculate the unweighted price index for 2020 using 2019 as the base year.

The unweighted price index is calculated as:

$$\text{Unweighted Price Index} = \frac{\sum P_n}{\sum P_0} \times 100$$

where $P_n$ is the price in the current year (2020) and $P_0$ is the price in the base year (2019).

$$\text{Unweighted Price Index} = \frac{565}{475} \times 100$$ $$\text{Unweighted Price Index} \approx 1.18947 \times 100$$ $$\text{Unweighted Price Index} \approx 118.95$$

The correct option is C.
The unweighted price index for 2020 using 2019 as the base year is $\boxed{\text{C. } \textbf{118.95}}$.

24. For the data in Table 5, calculate the Laspeyres price index for 2021 using 2020 as the base year.

The Laspeyres price index is calculated as:

$$\text{Laspeyres Price Index} = \frac{\sum (P_n \times Q_0)}{\sum (P_0 \times Q_0)} \times 100$$

where $P_n$ is the price in the current year (2021), $P_0$ is the price in the base year (2020), and $Q_0$ is the quantity in the base year (2020).

• Acid A: $100 \times 220 = 22000$
• Acid B: $260 \times 152 = 39520$
• Acid C: $60 \times 230 = 13800$
• Acid D: $145 \times 104 = 15080$

$$\sum (P_0 \times Q_0) = 22000 + 39520 + 13800 + 15080 = 90400$$

• Acid A: $107 \times 220 = 23540$
• Acid B: $260 \times 152 = 39520$
• Acid C: $95 \times 230 = 21850$
• Acid D: $160 \times 104 = 16640$

$$\sum (P_n \times Q_0) = 23540 + 39520 + 21850 + 16640 = 101550$$

$$\text{Laspeyres Price Index} = \frac{101550}{90400} \times 100$$ $$\text{Laspeyres Price Index} \approx 1.12334 \times 100$$ $$\text{Laspeyres Price Index} \approx 112.33$$

The correct option is B.
The Laspeyres price index for 2021 using 2020 as the base year is $\boxed{\text{B. } \textbf{112.33}}$.

25. For the data in Table 5, calculate the Paasche Price Index for 2021 using 2019 as the base.

The Paasche price index is calculated as:

$$\text{Paasche Price Index} = \frac{\sum (P_n \times Q_n)}{\sum (P_0 \times Q_n)} \times 100$$

where $P_n$ is the price in the current year (2021), $P_0$ is the price in the base year (2019), and $Q_n$ is the quantity in the current year (2021).

• Acid A: $107 \times 230 = 24610$
• Acid B: $260 \times 134 = 34840$
• Acid C: $95 \times 180 = 17100$
• Acid D: $160 \times 90 = 14400$

$$\sum (P_n \times Q_n) = 24610 + 34840 + 17100 + 14400 = 90950$$

• Acid A: $80 \times 230 = 18400$
• Acid B: $220 \times 134 = 29480$
• Acid C: $60 \times 180 = 10800$
• Acid D: $115 \times 90 = 10350$

$$\sum (P_0 \times Q_n) = 18400 + 29480 + 10800 + 10350 = 69030$$

$$\text{Paasche Price Index} = \frac{90950}{69030} \times 100$$ $$\text{Paasche Price Index} \approx 1.31754 \times 100$$ $$\text{Paasche Price Index} \approx 131.75$$

The correct option is A.
The Paasche Price Index for 2021 using 2019 as the base is $\boxed{\text{A. } \textbf{131.75}}$.