Sean has worked 66 hours over the last 10 days without a day off. he worked either a 6 hour day or an 8 hour day. during the 10 day period, how many days did sean work an 8 hour day?

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?