How many words, with or without meaning, can be formed with the letters of word ‘MONDAY’ assuming, that no letter is repeated, if 4 letters are used but the first letter is a vowel ?

Number of letters in word 'MONDAY' = 6 (all district)
    Number of vowels = 2 (O and A)
Number of letters to be used in 4 and first letter is a vowel,
   
             
Number of arrangements for box 1 =                                          (i)
(Two vowels for 1 box)
We now have 5 letters left and 3 boxes for them.
                            n = 5,  r = 3
∴          The number of permutations   ...(ii)
Hence, from (i) and (ii), the total number of permutations i.e., the number of words formed:
                                               = 2 x 60 = 120.