Question 203977: 1.find all real values of 'w' for which the statement
C(w+1,2)=9•C(w,1) is true.
2. while shooting arrows, William can hit an apple 9 out of 10 times. what is the probability that he will hit it exactly 4 out of the next 7 times.
*both of them were really hard for me to figure out. I appreciate your help.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 1.find all real values of 'w' for which the statement
C(w+1,2)=9•C(w,1) is true.
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(w+1)!/[w-1)!2!] = 9w
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Simplify:
[(w+1)w]/2 = 9w
w^2+w-18w = 0
w^2-17w = 0
w(w-17) = 0
Positive solution:
w = 17
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2. while shooting arrows, William can hit an apple 9 out of 10 times. what is the probability that he will hit it exactly 4 out of the next 7 times.
P(x=4) = 7C4(0.9)^4(0.1)^3 = 0.02296..
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Cheers,
Stan H.
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