In a smoking survey among boys between the ages of 12 and 17, 78% prefer to date nonsmokers, 1% prefer to date smokers, and 21% don't care. suppose seven such boys are selected randomly. let x equal the number who prefer to date nonsmokers and y equal the number who prefer to date smokers.

the answer is PMF(x,y) = Prob{X prefer nonsmokers and Y prefer smokers}

Support: 0<=X<=7, 0<=Y<=7, 0<=X+Y<=7.

PMF = Combinations(X of 7) * Combinations(Y of 7-X) * 0.78^X * 0.01^Y * 0.21^(7-X-Y)

(b)

The marginal PMF comes from summing the joint PMF over over Y. Alternatively, we can get it directly:

Support: 0<=X<=7

PMF(X) = Combinations(X of 7) * (0.78)^X * (0.22)^(7-X)  

brainliest plzz worked really hard on this thxx god bless

it is b)

hope this : )

step-by-step explanation:

geometry: triangles

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lessons

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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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