Cache effective access time calculation

Question

In order to calculate the effective access time of a memory sub-system, I see some different approaches, a.k.a formulas. All are reasonable, but I don't know how they differ and what is the correct one.

Assume a two-level cache and a main memory system with the following specs:

h1 = 80%       t1 = 10ns    L1 cache
h2 = 40%       t2 = 20ns    L2 cache
h3 = 100%      t3 = 100ns   Main memory

t1 means the time to access the L1 while t2 and t3 mean the penalty to access L2 and main memory, respectively.

I see two formulas as described below:

1- Teff = t1 + (1-h1)[t2 + (1-h2)t3] which will be 32. The logic behind that is to access L1, first. So, t1 is always accounted. Then with the miss ratio of L1, we access lower levels and that is repeated recursively. I agrre with this one! You can see further details here.

2- As discussed here, we can calculate that using Teff = h1*t1 + (1-h1)*h2*t2 + (1-h1)*(1-h2)*t3 which yields 24. However, that is is reasonable when we say that L1 is accessed sometimes. You can see another example here. Although that can be considered as an architecture, but we know that L1 is the first place for searching data. So, the L1 time should be always accounted.

Is there any suggestion for that?