ME-Practice Book Discrete Math Q#

Question

Comments

is answer 9?

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No 5

Answer 1

Divide the numbers from 1,2,3,4,5,6,7,8 as groups

like (1,8) (2,7) (3,6) (4,5)

Now we have four groups

Suppose take 4 numbers from 4 groups like 1,2,3,4 but some not equal to 9.

If we choose 5 numbers 1,2,3,4,8 or 1,2,3,4,7 then sum is 9.

Thus a minimum of 5 numbers are needed.

Comments

But here it is exactly 2 f them have sum=9..not atleast

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Choose any of 5 elements then (atleast)minimum 2 elements are there who sum = 9