Directly proportional, both increase/decrease, Multiple k(constant you needed to solve for)..
Inversely --one increases as the other decreases, increase the denominator & fraction gets smaller.... So
Problem:
Dirextly to X (× by X)
Inversely to Y, (÷ by Y)
Z= k X/Y
Solve, working backwards: Z =5 becomes
5 = k (X) ÷ (Y). And
X=15 and Y =9 becomes
5= k(15)/(9). Undo ÷9, ×9 both sides
45= k(15). Now undo ×15 by ÷15 both sides
45/15 = 3. So k=3, (also called your constant of variation)....and your Equation/Proportion becomes...
Z = 3X/Y
Use the new #s.... X=23, Y=14
Z= 3×23÷14 = 69/14. If they want spirochete answer divide and round to corresponding # if decimals
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Answer:
3876
Step-by-step explanation:
Given the following :
Fraternity members = 20
They are to attend 5 different parties in groups of 4
Meaning a group = 4 persons
Atleast one brother will attend exactly one of the parties. (the brothers are indistinguishable).
Then, exactly one brother at a party (20 - 1) = 19, since they are indistinguishable.
Group members are in 4's
19C4
From: nCr = n! /(n-r)! r!
19C4 = 19! / (19 - 4)! 4!
= 19! / 15! 4!
= (19 * 18 * 17 * 16) / (4 * 3 * 2)
= 93024 / 24
= 3876
