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## Homework Statement

If the class contains 7 mechanical, 6 civil and 5 electrical and we require that the 9 individuals who give their presentations on day 1 must include 3 mechanical, 3 civil and 3 electrical, how many different orders of presentation are there for day 1?

## Homework Equations

## The Attempt at a Solution

It looks like we have to combine 3 permutations together, taking only 3 students from each group.

I have no clue how to do this, I have tried reducing the problem to :

2 mechanical, 2 civil and 2 electrical and 1 per group must give a presentation.

I computed by hand the different orders of presentation, but then I don't know what formula to use to arrive at the same answer.

So If we have :

Mechanical students : A, B

Civil : C, D

Electrical : E, F

Then the different presentations on day 1 would be :

A, C, E

A, C, F

A, D, E

A, D, F

B, C, E

B, C, F

B, D, E

B, D, F

8*2*3 = 48 possible presentation order in this simple case, am I right?