A box contains 4 red pens, 3 blue pens, and 5 black pens. A pen is selected at random, not replaced, and then a second pen is selected. Find probability of: P(red, then blue)

geometry: triangles

solvers

lessons

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+

25.45584

(f+g)(x) = 3^x+10x+4x-2

      =3^x +14x-2

choice b

i think i remember taking that quiz.

a.

but im not sure so don't count on me.