From 1980 to 1990, the consumer price index (cpi) increased from 74.4 to 128.7. if a gallon of apple juice cost $0.78 in 1980 and the price of apple juice increased at the same rate as the cpi from 1980 to 1990, approximately how much did a gallon of apple juice cost in 1990?
a.$1.35
b.$1.55
c.$1.77
d.$1.49

A.$1.35

Explanation:

First, let's calculate the variation of the consumer price index (CPI) from 1980 to 1990:

(128.7-74.4)/74.4= 0,73

The increase of the consumer price index from 1980 to 11990 was 73%.

As the price of apple juice increased at the same rate as the CPI from 1980 to 1990, to find the cost of the gallon of apple juice in 1990, we have to calculate the 73% increase from the 1980 price:

$0.78*(1,73)= $1.35

The gallon of apple juice cost in 1990 $1.35.

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