cho tam giác abc có m là trung điểm của bc kẻ md // ac cắt ab tại d , me//ab cắt ac tại e chứng minh md=ae ,me=ad

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?