Quantitative models of music. Chance (Fall 2004) published a study on modeling a certain pitch of a musical composition. Data on 147 famous compositions were used to model the number of times (y) a certain pitch occurs—

called entropy—as a straight-line function of year of birth

(x) of the composer. On the basis of the scatterplot of the data, the standard deviation s of the model is estimated to be s = .1. For a given year (x), about 95% of the actual entropy values (y) will fall within d units of their predicted values. Find the value of d.