Demographics—Poverty: A study conducted by the Northern Aid Organization shows that the nu...

Demographics—Poverty: A study conducted by the Northern Aid Organization shows that the number of people identified as having incomes below poverty level in the northern provinces of a certain country can be modeled by

where x represents the population in thousands and f(x) represents the number of people identified as having incomes below poverty level, measured in thousands.

(a) Determine the differential dy for the model.

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(b) Suppose the population of the Prudential Province has increased from 20 thousand to 22 thousand. Use the differential to approximate the increase in number of people below poverty level.