Calculating CPI Stall

Question

In an example,

I don't really get how CPI stall is calculated here. I think CPI Stall = CPI Ideal + Memory Stall Cycles (At least this was given)?

From what I understand from the question: 2 = CPI Ideal. 0.02 = L1 miss rate. 25 = miss penalty. (but isnt this miss penalty for L2 cache?). .36 is num of memory instructions (why is it not .36 x .02 x 25 earlier?). .04 = ?? the 4% in braces? what does that mean? .005 = L2 miss rate.

Answer 1

I figured that the reason why 0.02 * 25 and 0.005 * 100 is without the reads/writes per prog is because the Instruction cache is always read, thus its 1 * ... where 1 can be omited