单项选择题 The price of the apple increases 20%, while the quantity demand for apple falls 40%. The price elasticity for the apple is :

单项选择题 The population follows an unknown distribution. The sample mean is 120 and the standard error of the sample mean is 6. The sample size is 120. The 90% confidence interval for the population mean is closest to:A.108.24 to 131.76.B.70.5 to 169.5.C.110.1 to 129.9.

单项选择题 In an oligopoly market, the demand curve for a manufacturer is approximate horizontal. This situation is most relevant to which of the following models?