An ethanol railroad tariff is a fee charge for shipments of ethanol on public railroads. The Agriculture Marketing Service publishes tariff rates for railroad-car shipments of ethanol in the Biofuel Transportation Database. Assuming that the standard deviation of such tariff rates is $1150, determine the probability that the mean tariff rate of 500 randomly selected railroad-car shipments of ethanol will be within $100 of the mean tariff rate of all railroad-car shipments of ethanol.

Data from 2005 for various age groups show that for each $100 increase in the median weekly income for whites, the median weekly income of blacks increases by $105. also, for workers of ages 25 to 54 the median weekly income for whites was $676 and for blacks was $527. (a) let w represent the median weekly income for whites and b the median weekly income for blacks, and write the equation of the line that gives b as a linear function of w. b = (b) when the median weekly income for whites is $760, what does the equation in (a) predict for the median weekly income for blacks?