gistfile1.txt

```
If an app invokes 1000 RPC calls to proceed,
and the 99th percentile delay for all of those
calls is 100ms, what is the likelihood that your
app will need to wait <=100ms to proceed?
```

Let's assume that the app needs all RPC to 
return before displaying something. (which is 
not necessarily the case)

Let $X_i$ be the response time of $RPC_i$,
and $T$ the overall response time.

We also assume the X_i independent.

We then have:
  T < t <=> (X_1 < t) ^ ... ^ (X_i < t) ^ ... ^ (X_1000 < t)  

P(T < t) =
  Product_i=1..1000 P(X_i < t)
  = (99/100) ^ 1000
  = (1 - 1/100) ^ 1000
  ~ exp(-1000/100) = exp(-10) = 0.000045