Operating systems paging question:

Suppose on-demand paging is employed in addition to TLB caching. The time for a TLB access (hit or miss) is T = 1 ns, a memory read M = 10 ns, and a disk read D = 10 ms. Let p_TLB = the probability of a TLB hit, and p = the probability of a page fault given a TLB miss.

a. What is a general formula for the average memory access time expressed as a function of T, M, D, p, and p_TLB?

b. Once parameter values are substituted, and assuming p = .001 and p_TLB = 90%, what is the average memory access time?