Statıstıcs I Deneme Sınavı Sorusu #821637
What must be the value of "a" if the table above is the probability distribution of variable X whose mean is 2.8?
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0.1 |
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0.2 |
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0.3 |
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0.4 |
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0.5 |
Yanıt Açıklaması:
If this is a probabilty distribution than the sum of all probabilities must be equal to 1. Thus 0.2+0.3+0.1+a+b=1 which means a+b=0.4, thus b=0.4-a. Also it is given that the mean of X is equal to 2.8.
Mean=Sum((X=x)P(X=x))
2.8=(1*0.2)+(2*0.3)+(3*0.1)+(4*a)+(5*b)
2.8=1.1+4a+5b
1.7=4a+5b=4a+5(0.4-a)
1.7=2-a
0.3=a
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