If the CPI was 90 in 1975 and is 225 today, then $100 today purchases the same amount of goods and services as

a.

$25.00 purchased in 1975
b.

$135.55 purchased in 1975
c.

$40.00 purchased in 1975
d.

$33.33 purchased in 1975

1 answer

To find out how much $100 today is equivalent to in 1975 dollars, we can use the Consumer Price Index (CPI).

Here are the steps to convert the current amount to the past amount:

  1. Identify the CPI values:

    • CPI in 1975 = 90
    • CPI today = 225
  2. Use the formula to find the equivalent amount in 1975: \[ \text{Equivalent amount in 1975} = \text{Amount today} \times \left(\frac{\text{CPI in 1975}}{\text{CPI today}}\right) \]

  3. Plug in the values: \[ \text{Equivalent amount in 1975} = 100 \times \left(\frac{90}{225}\right) \]

  4. Calculate: \[ \frac{90}{225} = 0.4 \] \[ \text{Equivalent amount in 1975} = 100 \times 0.4 = 40 \]

So, $100 today is equivalent to $40.00 in 1975.

The correct answer is: c. $40.00 purchased in 1975.