To furnish a room in a model home, an interior decorator is to select 2 chairs and 2 tables from a collection of chairs and tables in a warehouse that are all different from each other. If there are 5 chairs in the warehouse and if 150 different combinations are possible, how many tables are in the warehouse?

Respuesta :

Answer:

The number of tables in the warehouse are:

                             6

Step-by-step explanation:

We know that the method of combination is used to find the number of combinations possible in order to select r items from a set of n items

and is given by:

[tex]n_C_r=\dfrac{n!}{r!\times (n-r)!}[/tex]

Now, it is given that:

In order to furnish a room we have to select 2 chairs and 2 tables from 5 chairs and let there are t tables.

Also, the total number of combinations possible are: 150

i.e.

[tex]5_C_2\times t_C_2=150\\\\i.e.\\\\\dfrac{5!}{2!\times (5-2)!}\times \dfrac{t!}{2!\times (t-2)!}=150\\\\\dfrac{5!}{2!\times 3!}\times \dfrac{t(t-1)(t-2)!}{2\times (t-2)!}=150\\\\10\times \dfrac{t(t-1)}{2}=150\\\\5t(t-1)=150\\\\t(t-1)=30\\\\t^2-t-30=0\\\\t^2-6t+5t-30=0\\\\t(t-6)+5(t-6)=0\\\\(t+5)(t-6)=0\\\\i.e.\\\\t=-5\ or\ t=6[/tex]

But the number of table can't be negative.

Hence, we get:

[tex]t=6[/tex]

        There are 6 tables in the warehouse.

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