The graph shows the level of ibuprofen, y units, in a patient’s bloodstream x hours after the ibuprofen was taken. Select the correct answer to complete the blanks in the sentence: "The level of ibuprofen in the patient's bloodstream increased from hours to hours." Ibuprofin Graph Expand +

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?