OTTAWA SEEKS EXPLANATION OF CREDIT CARD RATES Minister of State for Finance Tom Hockin said he has asked the Canadian Bankers Association, an industry lobby group, for an explanation of the level of credit card interest rates. Hockin said he hopes to here the association's response on the "important" issue soon. Hockin was responding to questions in the House of Commons about why credit card rates, which run as high as 28 pct per year, remain high when other rates are falling. Today, the Canadian bank rate fell to 7.28 pct from 7.54 pct last week and the Canadian Imperial Bank of Commerce cut its prime rate, effective tomorrow, to 8.75 pct from 9.25 pct.