单选题
The price per share of stock X increased by 10 percent over the same time period that the price per share of stock Y decreased by 10 percent. The reduced price per share of stock Y was what percent of the original price per share of stock X?
(1)The increased price per share of stock X was equal to the original price per share of stock Y.
(2)The increase in the price per share of stock X was
(1)The increased price per share of stock X was equal to the original price per share of stock Y.
(2)The increase in the price per share of stock X was
【正确答案】
D
【答案解析】[解析] 设股票X每股的原始价格为x，则由(1)可得股票Y的每股原始价格为(1+10%)x，每股减少的钱为10%(1+10%)x，因此股票Y每股减少的钱与股票X的每股原始价格的比为[*]，所以(1)是充分的；根据(2)可得股票Y每股降的钱为[*]，也即股票Y每股减少的钱是股票X的每股原始价格的11%，所以(2)也是充分的。