Problem Solving

Request your help on this question, please explain the same.

To furnish a room in a model town home, an interior decorator is to select 2 chairs & 2 tables from a collections of chairs & 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?
1. 6
2. 8
3. 10
4. 15
5. 30
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Hi,

Let there be x tables

# of ways of selecting 2 tables from x tables = xC2 = x(x-1) / 2

# of ways of selecting 2 chairs from 5 chairs = 5C2 = 10

10 times x times (x-1) / 2 = 150

x times (x-1) = 30

Hence, x = 6.

Is the answer A? Thanks.

Yes correct answer is A. Thanks