[答案]

    借款实际利率=11.76%

    按贴现法付息的实际利率=8.7%

    有补偿性余额的借款实际利率=10%/1-15%×100%=11.76%

    按贴现法付息的实际利率=500×8%/500-500×8%×100%=8.7%