Section C ：Dictation
Many college students today own personal computers that cost anywhere from one thousand dollars to perhaps five thousand dollars or more.In addition, it is not uncommon for them to purchase software costing another several hundred dollars.Twenty years ago, computers were available,but they were very large and extremely expensive.Few if any individuals purchase computers for home use. Over the years, the price of the guts of a computer,its memory, has declined to less than a thousand of the price per unit of memory that prevailed twenty years ago.This is the main reason why computers cost so much less to day than they used to.Moreover, technological improvements have made it possible to manufacture memory circuitry that is small enough to fit into the portable personal computers that many of us own and use.
In short,as the price of computation has declined, the average consumer and bussiness have spent more on purchasing computers.By contrast, improved agricultural technology,high breed seeds,scientific animal breeding and so on, have vastly increased the amount of output a typical farmer can produce.The prices of goods,such as meats and grins have fallen sharply relative to the prices of most other goods in services.As agricultural prices have fallen,many households have decreased their total expenses on food. Even though the quantity of a product purchased generally increases when its prices falls,total expenses on it may decline.