24. If proved reserves of a mineral amount to twelve years of use at the current rate of consumption,
it is likely, though not certain, that we will run out of that mineral in about twelve years.
we are likely to run out of the mineral in less than twelve years if our rate of use has been
increasing.
if the good becomes more scarce relative to supply in the future, its price will rise and
thereby encourage both conservation and exploration.
if proved reserves diminish, lower prices will extend the day of exhaustion well into the
future.
25. Since 1979, the price of crude oil in real terms
has fluctuated but the overall trend has been downward.
rose during 1980-2000, but the price trend has been downward since 2000.
declined throughout most of the 1980s and 1990s, but in 2011 the price was once again
higher than the level of 1980.
all of the above are true.
26. Data on world reserves of minerals, gathered by Blackman and Baumol, show that between 1950 and
2000, production of most minerals
greatly exceeded the reserves available in 1950.
declined as depletion occurred.
greatly reduced the reserves available in 2000.
was limited to a fraction of the reserves available in 1950.
27. Fracking, a technique for breaking up (or fracturing) rock deep under the earth to release natural gas,
has
increased the price of natural gas.
decreased the supply of natural gas.
contaminated natural gas so it is no longer a “clean” fuel.
decreased the price of natural gas.
28. In the natural gas industry, recent technological improvements and the use of fracking have
increased the demand for natural gas, causing its price to rise.
increased the supply of natural gas, causing its price to decline.
reduced the demand for natural gas even though the proved reserves of the resource have
fallen.
resulted in sharply higher natural gas prices because of the dangers that accompany
fracking.
29. Natural gas prices in real terms have