Help please, i'm stomped on this one:?

Question

In a class test there are 5 questions. One question has been taken

from each of the 4 chapters . The first two chapters have 3 questions

each and the last two chapters have 6 questions each .

the fourth question can be picked from any of the chapters.

How many different question papers could have been prepared?

Answer 1

This looks tricky , so break it down into simple steps:-

Ist question must be from Ch 1, can be chosen in 3 ways.

2nd .................................... 2 ..........................3 ........

3rd ......................................3.... 6.........

5th .......................................4... 6........

That's 3*3*6*6 ways altogether.

Now the tricky part:-

The 4th question can be chosen in 2 ways from the 1st, 2 from the 2nd, 5 from the 3rd, and 5 from the 4th, because we can't count the Qs already chosen again.           That's 2*2*5*5 ways.

Multiply those ways togeher for the total ways the Qs can be set