Suppose a computer has an L1 cache and a main memory. The time to access a word in the L1 cache is 0.001 ms. The access time of the main memory is 0.125 ms.

a) Suppose the hit rate is 90%. What is the average access time? Show your calculations.

b) What must the hit rate be to achieve an average access time of .007 ms? Show your calculations so someone else could reproduce the calculation with different numbers. (Do not post the same answer found in Chegg)