A series of extra rehearsals commenced in April. Each week participants could choose extra dancing rehearsals or extra singing rehearsals.

A matrix equation used to determine the number of students expected to attend these extra rehearsals is given by

where is the column matrix that lists the number of students attending in week .

The attendance matrix for the first week of extra rehearsals is given by

1. Calculate the number of students who are expected to attend the extra singing rehearsals in week 3.   (1 mark)
   

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2. Of the students who attended extra rehearsals in week 3, how many are not expected to return for any extra rehearsals in week 4?   (1 mark)
   

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