ECMT1010 - Revision Questions (1 Viewer)

[yvonne_710]

can someone just tell me from q11(i), how to do E(Y)???i got E(X.Y)..but errrrrrrr cant get the right answer.so i think my problem here is E(Y)!

 

[sarevok]

E(Y) = 1(.04+.14+.23+.07) + 2(.07+.17+.23+.05) = whatever the answer is

 

[yvonne_710]

yah, i did that way, but the answer wasnt correct..

 

[myg0t]

can someone just tell me from q11(i), how to do E(Y)???i got E(X.Y)..but errrrrrrr cant get the right answer.so i think my problem here is E(Y)!

alternatively draw up the tables that you learnt in the workshops, then you can calculate your average and variance with ease...



Does anyone know how to do:
Q 13 and 19C??

 

[yvonne_710]

alternatively draw up the tables that you learnt in the workshops, then you can calculate your average and variance with ease...



Does anyone know how to do:
Q 13 and 19C??

i got E(X,Y)=3.89,and then i used E(x,y)-E(x)*E(y), but cant get it ,i dont know where is the problem..
btw, q19(C) is: 0.18/(0.18+0.56)

 

[stazi]

alternatively draw up the tables that you learnt in the workshops, then you can calculate your average and variance with ease...



Does anyone know how to do:
Q 13 and 19C??

13:
Sumx=56 SumXsq=360
so mean = 56/n = 56/10 = 5.6
Variance = E(Xsq)-[E(X)]sqwaaared. = 360/10 - 5.6sq
Don't forget to square root it afterwards to get standard deviation.

19c"
P(Wholesale|Deluxe) = P(Wholesale and deluxe)/P(Deluxe)

 

[kow_dude]

alternatively draw up the tables that you learnt in the workshops, then you can calculate your average and variance with ease...



Does anyone know how to do:
Q 13 and 19C??

For question 13, i got a different answer to the solutions

 

[yvonne_710]

can someone show the whole process for Q11 (i), thanks a lot ,i just need to check what's wrong with mine...

 

[sarevok]

i just did that question and got the right answer...

3.89 - (2.59)(1.52) = -0.0468

 

[stazi]

For question 13, i got a different answer to the solutions

did u have the same working as me

 

[myg0t]

did u have the same working as me

stas continue with your working for Q13 u havent asnwered it

 

[myg0t]

can someone show the whole process for Q11 (i), thanks a lot ,i just need to check what's wrong with mine...

ok you need to draw up a new table.

your first column is the probabilities (1 through 4)

next you'll see your conditional distribution values of X are .11, .31, .46 and .12
this will form your second column.

your third column x P(x) is simply the corresponding values multiplied together. Add these up and you get your average.

then your fourth column is simply the same as column 1 but square each value

your final column is going to be xsquard p (X) which is column 4 multiplied by column 2. to find your variance, you need to square the answer you got for your average and minus it from the answer for the sum of this column.

 

[kow_dude]

did u have the same working as me

Nevermind, i got it.... miscalulation in the standard dev.

 

[stazi]

ok
stdev = 4.64
mean = 5.6
X(bar) +/- t(alpha/2,n-1) (s/rtN)
5.6 +/- 2.262 (4.64/3.16) = {2.281, 8.919}

hmm the answer differs to the answers. it seems correct though

 

[yvonne_710]

ok you need to draw up a new table.

your first column is the probabilities (1 through 4)

next you'll see your conditional distribution values of X are .11, .31, .46 and .12
this will form your second column.

your third column x P(x) is simply the corresponding values multiplied together. Add these up and you get your average.

then your fourth column is simply the same as column 1 but square each value

your final column is going to be xsquard p (X) which is column 4 multiplied by column 2. to find your variance, you need to square the answer you got for your average and minus it from the answer for the sum of this column.

thanks a lot~~~~~~~~~~

 

[kow_dude]

ok
stdev = 4.64
mean = 5.6
X(bar) +/- t(alpha/2,n-1) (s/rtN)
5.6 +/- 2.262 (4.64/3.16) = {2.281, 8.919}

hmm the answer differs to the answers. it seems correct though

st dev is 2.27

 

[stazi]

st dev is 2.27

isn't it 2.15.
36-31.36 = 4.64
sqrt = 2.15

 

[kow_dude]

isn't it 2.15.
36-31.36 = 4.64
sqrt = 2.15

haha... u made the same mistake as i did. You forgot the 'n' in you standard dev formula

 

[yvonne_710]

do we need to know Correlation? the formula looks horrible.............~~~~~~~~~

 

[kow_dude]

Whatever that is i think it's better to get a good night's sleep...

i'm off... good luck peoples