Background Paragraph: Storing large volumes of data – When storing XML to either file or database, the volume of data a system produces can often exceed reasonable limits, with a number of detriments: the access times go up as more data is read, CPU load goes up as XML data takes more power to process, and storage costs go up. By storing XML data in Fast Infoset format, data volume may be reduced by as much as 80 percent. 
Story: Robin had a busy day storing XML. At 5 AM, he stored 220 Gigabytes to the database. At 6 AM, he stored 330 Gigabytes to the database. At 7 AM, he stored 440 Gigabytes to the database. At 8 AM, he got breakfast. At 9 AM, he stored 550 Gigabytes to the database. At 10 AM, he stored 660 Gigabytes to the database. At 11 AM, she went to sleep to finish storing XML later that day. 
Question: What time did storage costs go up:  6 AM or 11 AM?
6 AM.