请教一个体系结构方面的问题？

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该问题出自《计算机体系结构——量化研究方法》一书
Consider a branch-target buffer that has penalties of 0,2,and 2 clock cycles for correct conditional branch prediction,incorrect prediction,and a buffer miss, respectively.Consider a branch-target buffer design that distinguishes conditional and unconditional branches,storing the target address for a conditional branch and the target instruction for an unconditional branch.
1. What is the penalty in clock cycles when an unconditional branch is found in the buffer?
2. Determine the improvement from branch folding for unconditional branches. Assume a 90% hit rate, an unconditional branch frequency of 5%, and a 2-cycle penalty for a buffer miss. How much improvement is gained by this enhancement? How high must the hit rate be for this enhancement to provide a performance gain?