<< Chapter < Page Chapter >> Page >

(See Exercise 4 from "Problems On Random Vectors and Joint Distributions", m-file npr08_04.m ). As a variation of [link] , suppose a pair of dice is rolled instead of a single die. Determine the joint distribution for { X , Y } and determine E [ Y ] .

npr08_04 Answers are in X, Y, P jcalc- - - - - - - - - - - - EX = X*PX'EX = 7 EY = Y*PY'EY = 3.5000 EX2 = (X.^2)*PX'EX2 = 54.8333 EY2 = (Y.^2)*PY'EY2 = 15.4583
Got questions? Get instant answers now!

(See Exercise 5 from "Problems On Random Vectors and Joint Distributions", m-file npr08_05.m ). Suppose a pair of dice is rolled. Let X be the total number of spots which turn up. Roll the pair an additional X times. Let Y be the number of sevens that are thrown on the X rolls. Determine the joint distribution for { X , Y } and determine E [ Y ] .

npr08_05 Answers are in X, Y, P, PY jcalc- - - - - - - - - - - - EX = X*PX'EX = 7.0000 EY = Y*PY'EY = 1.1667
Got questions? Get instant answers now!

(See Exercise 6 from "Problems On Random Vectors and Joint Distributions", m-file npr08_06.m ). The pair { X , Y } has the joint distribution:

X = [ - 2 . 3 - 0 . 7 1 . 1 3 . 9 5 . 1 ] Y = [ 1 . 3 2 . 5 4 . 1 5 . 3 ]
P = 0 . 0483 0 . 0357 0 . 0420 0 . 0399 0 . 0441 0 . 0437 0 . 0323 0 . 0380 0 . 0361 0 . 0399 0 . 0713 0 . 0527 0 . 0620 0 . 0609 0 . 0551 0 . 0667 0 . 0493 0 . 0580 0 . 0651 0 . 0589

Determine E [ X ] , E [ Y ] , E [ X 2 ] , E [ Y 2 ] , and E [ X Y ] .

npr08_06 Data are in X, Y, P jcalc- - - - - - - - - - - - EX = X*PX'EX = 1.3696 EY = Y*PY'EY = 3.0344 EX2 = (X.^2)*PX'EX2 = 9.7644 EY2 = (Y.^2)*PY'EY2 = 11.4839 EXY = total(t.*u.*P)EXY = 4.1423
Got questions? Get instant answers now!

(See Exercise 7 from "Problems On Random Vectors and Joint Distributions", m-file npr08_07.m ). The pair { X , Y } has the joint distribution:

P ( X = t , Y = u )
t = -3.1 -0.5 1.2 2.4 3.7 4.9
u = 7.5 0.0090 0.0396 0.0594 0.0216 0.0440 0.0203
4.1 0.0495 0 0.1089 0.0528 0.0363 0.0231
-2.0 0.0405 0.1320 0.0891 0.0324 0.0297 0.0189
-3.8 0.0510 0.0484 0.0726 0.0132 0 0.0077

Determine E [ X ] , E [ Y ] , E [ X 2 ] , E [ Y 2 ] , and E [ X Y ] .

npr08_07 Data are in X, Y, P jcalc- - - - - - - - - - - - EX = X*PX'EX = 0.8590 EY = Y*PY'EY = 1.1455 EX2 = (X.^2)*PX'EX2 = 5.8495 EY2 = (Y.^2)*PY'EY2 = 19.6115 EXY = total(t.*u.*P)EXY = 3.6803
Got questions? Get instant answers now!

(See Exercise 8 from "Problems On Random Vectors and Joint Distributions", m-file npr08_08.m ). The pair { X , Y } has the joint distribution:

P ( X = t , Y = u )
t = 1 3 5 7 9 11 13 15 17 19
u = 12 0.0156 0.0191 0.0081 0.0035 0.0091 0.0070 0.0098 0.0056 0.0091 0.0049
10 0.0064 0.0204 0.0108 0.0040 0.0054 0.0080 0.0112 0.0064 0.0104 0.0056
9 0.0196 0.0256 0.0126 0.0060 0.0156 0.0120 0.0168 0.0096 0.0056 0.0084
5 0.0112 0.0182 0.0108 0.0070 0.0182 0.0140 0.0196 0.0012 0.0182 0.0038
3 0.0060 0.0260 0.0162 0.0050 0.0160 0.0200 0.0280 0.0060 0.0160 0.0040
-1 0.0096 0.0056 0.0072 0.0060 0.0256 0.0120 0.0268 0.0096 0.0256 0.0084
-3 0.0044 0.0134 0.0180 0.0140 0.0234 0.0180 0.0252 0.0244 0.0234 0.0126
-5 0.0072 0.0017 0.0063 0.0045 0.0167 0.0090 0.0026 0.0172 0.0217 0.0223

Determine E [ X ] , E [ Y ] , E [ X 2 ] , E [ Y 2 ] , and E [ X Y ] .

npr08_08 Data are in X, Y, P jcalc- - - - - - - - - - - - - EX = X*PX'EX = 10.1000 EY = Y*PY'EY = 3.0016 EX2 = (X.^2)*PX'EX2 = 133.0800 EY2 = (Y.^2)*PY'EY2 = 41.5564 EXY = total(t.*u.*P)EXY = 22.2890
Got questions? Get instant answers now!

(See Exercise 9 from "Problems On Random Vectors and Joint Distributions", m-file npr08_09.m ). Data were kept on the effect of training time on the time to performa job on a production line. X is the amount of training, in hours, and Y is the time to perform the task, in minutes. The data are as follows:

P ( X = t , Y = u )
t = 1 1.5 2 2.5 3
u = 5 0.039 0.011 0.005 0.001 0.001
4 0.065 0.070 0.050 0.015 0.010
3 0.031 0.061 0.137 0.051 0.033
2 0.012 0.049 0.163 0.058 0.039
1 0.003 0.009 0.045 0.025 0.017

Determine E [ X ] , E [ Y ] , E [ X 2 ] , E [ Y 2 ] , and E [ X Y ] .

npr08_09 Data are in X, Y, P jcalc- - - - - - - - - - - - EX = X*PX'EX = 1.9250 EY = Y*PY'EY = 2.8050 EX2 = (X.^2)*PX'EX2 = 4.0375 EY2 = (Y.^2)*PY' EXY = total(t.*u.*P)EY2 = 8.9850 EXY = 5.1410
Got questions? Get instant answers now!

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Applied probability. OpenStax CNX. Aug 31, 2009 Download for free at http://cnx.org/content/col10708/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Applied probability' conversation and receive update notifications?

Ask