Jamal is planning to invest up to $15000 in City Bank or State Bank. He wants to invest at least $1000 in City Bank, but no more than $7000, since State Bank does not insure more than $12,000, he wants to invest no more than this amount in State Bank. The interest at City Bank is 4% and the interest at State Bank is 11%. How much should he invest in each bank to earn the most interest?
