adjustably pegging an exchange rate means allowing it a range within which the underlying true value may sit without changing the actual pegged rate of exchange. For consistency and to avoid the occasion for arbitrage, the endpoints of each range must not depend on how the rate is quoted , for example, as dollar. This condition is not met, however, when the pegged rate is arithmetically centered within each range. For example, if the range is $1.5 to $2.5 dollars per pound, pegging the rate at the arithmetic center of the range would mean an exchange rate of $2 per pound. Quoting in pounds to the dollar, However, the range is 0.4 to about 0.67 per dollar, and the pegged rate at 0.5 per dollar is off from the arithmetic center of about 0.63 per dollar. When the endpoints of range are the same both ways,the arithmetic centers are not the same; when the pegged rate is the same both ways, the endpoints cannot be both the same and equidistant from pegged rate