Respuesta :
The percent increase in the price index from 1960 to 1970 is:
% increase in price index = (38.8 – 29.6) * 100% / 29.6
% increase in price index = 31.08%
Therefore the price of a dozen tangerines in 1970 (X) is:
31.08 = (X - $0.31) * 100 / $0.31
X = $0.41