# Question b13c2

Sep 16, 2016

Let's call them A1, A2, A3 for maths, B1, B2 for physics, and C1, C2 for philosophy.

#### Explanation:

Within the groups there are 6 posibilities for the A-group:
123, 132, 213, 231, 312, 321
For the other groups there are only 1,2 and 2,1.

The groups themselves can be ordered in 6 ways (as for any 3 items).

For the total number of orders we multiply all possibilities:

$N = 6 \times 6 \times 2 \times 2 = 144$

Extra : the total number of orders if groups don't have to stay together is: 7xx6xx5xx4xx3xx2xx1=7! =5040#