A quality control inspector samples 2 computer chips from a box containing 13 computer chips. If the box contains 3 defective chips, in how many ways can he select a sample so that at least one of the chips is defective?

The number of ways to select a sample of 2 computer chips so that at least one of the chips is defective is 33 ways.

Step-by-step explanation:

The box contains 13 computer chips. Of these 13 chips 3 are defective and 10 are good.

A quality control inspector samples 2 computer chips.

The number of ways to select at least 1 defective chip is:

n (At least 1 defective chip) = n (1 defective chip) + n (2 defective chips)

The number of ways to select 1 defective chip is: ways.

The number of ways to select 2 defective chips is: ways.

n (At least 1 defective chip) = n (1 defective chip) + n (2 defective chips)

                                             = 30 + 3

                                             = 33

Thus, the number of ways to select a sample of 2 computer chips so that at least one of the chips is defective is 33 ways.

geometry: triangles

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answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

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