A consumer price index (CPI) for a certain city in 2020 was calculated using a basket of goods with a base year of 2018. The index numbers for three categories of goods (A, B, and C) were 120, 110, and 130 respectively. If the index numbers for the same categories in 2019 were 115, 105, and 125 respectively, what can we infer about the accuracy of the CPI using the time reversal test?
1
The CPI accurately reflects changes in the cost of living between 2018 and 2020.
2
The CPI underestimates the changes in the cost of living between 2018 and 2020.
3
The CPI overestimates the changes in the cost of living between 2018 and 2020.
4
The CPI is invalid and cannot be used to measure changes in the cost of living.