Question 1174675
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(a)   2*4*4   ways.


      There are 2 possibilities for the first digit (the digits 3 or 4) and 4 possibilities for the 2nd and 3rd positions.    



(b)    2*3*2  ways.


      There are 2 possibilities for the first position (the digits 3 or 4);


      3 possibilities of remaining digits for the 2nd position and

      2 possibilities of remaining digits for the last position.