A box contain 9 novels, 7 biographies, and 5 reference books. Alyssa randomly chooses a book, then she randomly chooses another

book without replacing the first book.
What is the probablity that she chooses two biographies? Write answer as decimal

Mathematics

1 answer:

Tanzania [10]4 years ago

5 0

$first\ book:\\9\ novels+7\ biographies+5\ reference=21\ all\ books\\probability:\\P_1("chooses\ biographie")= \frac{7}{21} = \frac{1}{3} \\\\second\ book:\\9\ novels+6\ biographies+5\ reference=20\ all\ books\\probability:\\P_2("chooses\ biographie")= \frac{6}{20} = \frac{3}{10}\\\\the\ probablity\ that\ Alyssa\ chooses\ two\ biographies:\\P("two\ biographies")=P_1\cdot P_2= \frac{1}{3}\cdot \frac{3}{10} = \frac{1}{10} =0.1\\\\Ans.\ Probability\ is\ 0.1$

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Llana [10]

Answer:

$\huge\boxed{x=2\ and\ y=-3}$

Step-by-step explanation:

$22(x+yi)+(28+4i)=72-62i\\\\22x+22yi+28+4i=72-62i\\\\(22x+28)+(22y+4)i=72-62i\Rightarrow22x+28=72\ \wedge\ 22y+4=-62\\\\22x+28=72\qquad|\text{subtract 28 from both sides}\\22x=44\qquad|\text{divide both sides by 22}\\\boxed{x=2}\\\\22y+4=-62\qquad|\text{subtract 4 from both sides}\\22y=-66\qquad|\text{divide both sides by 22}\\\boxed{y=-3}$