Editing Consumer price index (section)

=== For a single item ===
<math>\text{consumer price index} =\frac{\text{market basket of desired year}}{\text{market basket of base year}} \times \text{100}
</math>

or

<math>\frac{\text{CPI}_2}{\text{CPI}_1}= \frac{\text{price}_2}{\text{price}_1} </math>
:''Where 1 is usually the comparison year and CPI<sub>1</sub> is usually an index of 100.''

Alternatively, the CPI can be performed as <math>\text{CPI} = \frac{\text{updated cost}}{\text{base period cost}} \times 100</math>. The "updated cost" (i.e. the price of an item at a given year, e.g.: the price of bread today) is divided by that of the initial year (the price of bread in 1970), then multiplied by one hundred.<ref>{{cite web |url=http://student.education2020.com/activities/lecture.aspx?keystr=12362&order=06010210&stbl=2196464 |website=Education 2020 Homeschool Console |title=subject Economics, lecture "Inflation" |url-access=subscription}} Formula described within.</ref>{{Better source needed|date=April 2024}}