4.3 solutions

# Suppose x has the following probability distribution

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7. Suppose X has the following probability distribution below. Find the mean of X. X -1 0 1 P(x) .50 .30 .20 a. 0 b. .33 c. -.30 = -1(.5) + 0(.3) + 1(.2) d. None of the above 1

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Suppose X, the number of teller windows open at any given time has the following probability distribution. X 1 2 3 4 P(X) .10 .25 .50 .15 8. How many teller windows will be open on average, over the long term? E(X)=1x.10 + 2x.25 + 3x.50+4x.15 = 2.7 9. How variable is the number of open teller windows? Find the appropriate value. V(X) = E(X 2 ) – E(X) 2 E(X 2 ) = 1x.10 + 4x.25 + 9x.50 + 16x.15 = 8 V(X) = E(X 2 ) – E(X) 2 = 8 – 2.7 2 = .71. SD = square root = .84 Brandt Data Solutions is a retail computer store that sells network cables in retail lengths of 3, 5, 10 and 25 feet. From past records they know that the quantity of sales follows the following probability distribution. X 3 5 10 25 P(X) 0.1 0.2 0.5 0.2 10. Find E(X) and interpret 3x.1+5x.2+…25x.2=11.3 The mean length of cables sold at Brandt Data Solutions is 11.3 feet. 11. Find SD(X) and interpret E(X 2 )=3 2 x.1+5 2 x.2+…+25 2 x.2=180.9 E(X)=11.3 so V(X) = 180.9-11.3 2 =53.21 and SD(X)=7.29 Data on 1,000 executives at Dogs R Us were collected and are summarized below.
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