An estimated 341,000 Ohio college students with low or moderate incomes will see the interest rate on their federal loans double this summer. Interest on new subsidized Stafford loans taken out after July 1 will double to 6.8 percent from 3.4 percent, unless Congress votes to extend the lower rate. The rate hike will affect more than 7.8 million undergraduates nationwide and will cost the average borrower an additional $2,800 on average over a 10-year repayment period, according to the U.S. Public Interest Research Group. Interest on the loans is paid by the government while a student is in school and for six months after graduation.