(i) There are 11 letters in the word 'MATHEMATICS' . Out of these letters M occurs twice, A occurs twice, T occurs twice and the rest are all different. Hence, the total number of arrangements of the given letters =11!(2!)×(2!)×(2!)=4989600.=11!(2!)×(2!)×(2!)=4989600. (ii) The given word contains 4 vowels AEAI as one letter, we have to arrange 8 letters MATHMTCS + AEAI, out of which M occurs twice, T occurs twice and the rest are all different. So, the number of all such arrangements =8!(2!)×(2!)=10080.=8!(2!)×(2!)=10080. Now, out of 4 vowels, A occurs twice and the rest are all distinct. So, the number of arrangements of these vowels =4!2!=12.=4!2!=12. Hence, the number of arrangement in which 4 vowels are together =(10080×12)=120960.