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VMO 2012 Question 5

VMO · VMO 2012

Question 5

A group consists of five girls, denoted by $G_1,G_2,G_3,G_4,G_5$, and twelve boys. Seventeen chairs are arranged in a row. Seat the group so that all the following conditions hold:
1. Every chair has exactly one occupant.
2. From left to right, the girls occur in the order $G_1,G_2,G_3,G_4,G_5$.
3. At least three boys sit between $G_1$ and $G_2$.
4. At least one and at most four boys sit between $G_4$ and $G_5$.
How many such arrangements are there? Two arrangements are different if some chair has different occupants in them.