Consider a computer system that has cache memory, main memory (RAM) and disk, and an operating system that uses virtual memory. It takes $1$ nsec to access a word from the cache, $10$ nsec to access a word from the RAM, and $10$ ms to access a word from the disk. If the cache hit rate is $95\%$ and main memory hit rate (after a cache miss) is $99\%$, what is the average time to access a word?