Pete is curious about how many hours of TV his family watches each week. Upon asking his family members, he found that they watched 20.4 hours of TV last week versus 11.9 hours of TV this week. What is the percent of decrease in the weekly amount of TV watched by Pete's family?

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ac=26 and ch=8, find bh.

The mountain springs water company has two departments, purifying and bottling. the bottling department received 67,000 liters from the purifying department. during the period, the bottling department completed 65,000 liters, including 3,000 liters of work in process at the beginning of the period. the ending work in process was 5,000 liters. how many liters were started and completed during the period?