The NVIDIA Tesla K-20X GPU has 2688 cores, each operating at a 732-MHz frequency. Further, the GPU has 6 GB of DRAM with a bandwidth of 250 GB/sec that is shared among all the cores. If a password hashing scheme (PHS) takes 2 ms to compute a password: a. How many passwords can be tested by the GPU in one hour if the PHS consumes no memory? b. How many cores can work simultaneously if each hash computation requires 20 MB of DRAM? How many passwords can now be tested by the GPU in one hour?