I used a movie ticket as the good I chose. A standard movie ticket 40 years ago was around $5 with an old index value of 100 (between 1984-1986). Today’s price is around $15 with a CPI value of 226.238 (as of February 2024).
In using the formula for the current price, it would be $11.31 had it increased at the same rate as inflation. There is a $3.69 difference in which I believe may be due to factors like changes in production costs, technology (e.g., digital projection), and amenities offered by modern theaters such as lounging seats, advanced sound systems, and larger screens.