Question

In 1980, when the consumer price index (CPI) was 82.4, Ivan purchased a house for $71,900. Assuming that the price of houses increased at the same rate as the CPI from 1970 to 1980, approximately how much would the house have cost in 1970, when the CPI was 38.8?

Answer 1

For apex it is $33,900

Answer 2

Assuming simple proportion, and x=1970 cost of the house, x/71900=38.8/82.4, so x=71900×38.8/82.4=$33856 approx.