Q.6 a) Let X be a random variable with probability distribution -1 1 2 3 f(x) 0.125 0.50 0.20 0.05 0.125 Find E(X) and Var (X). b) If 70% of the voters in a large district prefer candidate A, what is the probability that in a sample of 10 voters exactly 6 will prefer candidate A? c) The mean height of soldiers is u = 72 inches with a variance ofo ² = 16 (inches). Assuming the distribution of heights to be normal, how many soldiers in a regiment of 1000 would you expect to be over 75 inches tall?

A First Course in Probability (10th Edition)
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Chapter1: Combinatorial Analysis
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Q.6 a)
Let X be a random variable with probability distribution
X
-1
1
2
3
f(x)
0.125
0.50
0.20
0.05
0.125
Find E(X) and Var (X).
b)
If 70% of the voters in a large district prefer candidate A, what is the probability that in a sample
of 10 voters exactly 6 will prefer candidate A?
с)
The mean height of soldiers is µ = 72 inches with a variance ofơ² = 16 (inches)² . Assuming the
distribution of heights to be normal, how many soldiers in a regiment of 1000 would you expect
to be over 75 inches tall?
Transcribed Image Text:Q.6 a) Let X be a random variable with probability distribution X -1 1 2 3 f(x) 0.125 0.50 0.20 0.05 0.125 Find E(X) and Var (X). b) If 70% of the voters in a large district prefer candidate A, what is the probability that in a sample of 10 voters exactly 6 will prefer candidate A? с) The mean height of soldiers is µ = 72 inches with a variance ofơ² = 16 (inches)² . Assuming the distribution of heights to be normal, how many soldiers in a regiment of 1000 would you expect to be over 75 inches tall?
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