System is like
CPU ->LEVEL1 CACHE -> LEVEL2 CACHE
So effective memory access time
=Hit of level 1 *(Access time of level 1) + (Miss of level 1)(Access of level 1 + access of level 2)
=.95*(10) + 0.05 *(100+10)=15 sec
But in question they asked for AVERAGE ACCESS TIME FOR WORD
so its = Total time /Number of words.
total time = 100*10 + 4900*110= 540000
number of words are 5000
so time = 540000/5000=108.nano sec