In a 2015 study entitled How Undergraduate Students Use Credit Cards, it was reported that undergraduate students have a mean credit card balance higher than $3000. This figure was an all-time high and had increased 42% over the previous five years. Assume that a current study is being conducted to determine if it can be concluded that the mean credit card balance for undergraduate students has continued to increase compared to the report. They want to test to see if the balance for students in 2019 is higher than the balance for students in 2015. See the sample below of undergraduate students in 2015 and different undergraduate students in 2019.

Students in 2015	Students in 2019
2500	3300
2200	5450
1500	8000
930	2000
5300	870
1150	250
2700	3000
3300	2200

What is the difference between the means of credit card balances for students in 2015 and students in 2019?