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#1 Help Me ! » help!!! » 2008-10-11 10:21:29

Janiffer
Replies: 1

Suppose the rv Y is normally distributed  with mean 2,  and variance  25

a) Find the probability that Y exceeds 1, given that Y is positive.

b) Find the expected value of Y , given that Y is positive


HINT: For b) first derivative the cdf of the rv given by X= (X/ Y>0)

Can some one help plssssssssssssss

#2 Help Me ! » differentiation » 2008-10-10 12:30:46

Janiffer
Replies: 1

Can someone please help me to get the 1st and second derivative of the following..

m(t)= [e^((k)((e^t)-1)]/ ((1-bt)^a))...

#4 Help Me ! » stats!!!! » 2008-08-28 19:35:54

Janiffer
Replies: 3

in a uni games tournament, 64 students are about to participate in a chess knockout tournament.

The  first round consists of 32 games, with 2 students per game.

The 32 winners of the first round get to play in the 2nd round, which consists of 16 games, and so on, until an overall winner is declared in the 6th round.

(in the case of a draw n any game, a coin is tossed to determine the winner)

a) In how many differrent ways can the 64 participating students be paired up on the first round? (order not required)

b)Suppose the 64 players are of equal ability, and pairing up is purely random on each round.

Find the probability that EVA and BRETT( 2 of the 64 students) will get to play each other at some stageduring the knockout competition....

Can some please help me with this question.....

Thanks loads!!!!!!!!!!!

( working please;))

#5 Help Me ! » Limits of functions of two variables » 2008-05-25 20:16:21

Janiffer
Replies: 0

lim (x,y) approaches (0,0): sinh ((x^2) +(y^2)) /((x^2) +y^2))

How do u show the workings??

b) lim (x,y) approaches (0,0) : ((x^3) -(y^3))/((x^2) +(y^2)))

Plese show me how to write it out as I don't know how to explain it... Sorry for the trouble...

#7 Help Me ! » Differential equations » 2008-05-25 13:38:51

Janiffer
Replies: 3

A nitric acid solution flows at a constant rate of 6 litres/ min into a tank which initially held 200 litres of 0.5% nitric acid solution. The solution in the tank is kept well mixed through stirring and flows out of the tank at a rate of 8 litres / min. If the solution entering the tank is 20% nitric, then

a) determine the volume of nitric acid in the tank after t minutes.

b) determine when the % of nitric acid reaches 10%.:|

#8 Help Me ! » Determinants » 2008-05-25 12:57:52

Janiffer
Replies: 2

Suppose A  is a square matrix such that det A^4=0. Esplain why A cannot be invertible.

b) Consider a square invertible matrix A. Ifthe entries of A are integers and det A= +/- 1, then show that the entries of A inverse are integers....:D

#9 Help Me ! » Integration » 2008-05-25 04:47:25

Janiffer
Replies: 1

how do u  integrate

1/((x(1- (ln^2(x))^0.5))

#10 Help Me ! » Matrix » 2008-05-12 03:32:12

Janiffer
Replies: 9

suppose A is a 4x3 matrix and C is a 3x4 matrix such that CA=I3. Suppose further that for some given b in R4, the equation Ax=b has atleast one solution. Show that this solution is unique...

#11 Re: Help Me ! » Intermediate forms » 2008-05-10 03:00:44

Thanks a lot!!! that helped;))

#13 Help Me ! » Intermediate forms » 2008-05-07 03:51:36

Janiffer
Replies: 4

How do you finf the limits for the following

a) lim (as x approaches 1) ((ln(sinh(x-1))/(ln ((x^2)-1))?

b) lim( x approaches 0) xln(tanh(x))?

#14 Help Me ! » Exponential and logarithmic functions » 2008-04-27 20:02:18

Janiffer
Replies: 2

how do you show that
lnx<(x^1/2)  x>0...

#15 Help Me ! » Hyperbolic functions » 2008-04-27 19:55:00

Janiffer
Replies: 2

I tried dis question over and over and i cldnt get it rite!!1

An electricity cable between two poles A and B of equal height placed 14 metres apart has the shape of a catenary:

y=20cosh(x/20) - 15, where x and y are measured in metres.

a) find the slope where the cable meets the pole B..
A: I found dy/dx @ x=7 and my answer was 0.35712

b)Find the angle between cable B and the pole?!
How do u do this??:o

#16 Re: Help Me ! » Taylor polynomials » 2008-04-27 01:26:25

Also if you had to find an approximate value for e... will 7^1/2 be useful??

#17 Re: Help Me ! » Taylor polynomials » 2008-04-26 12:29:49

thnks a lot for the reply!!

#19 Help Me ! » Taylor polynomials » 2008-04-26 03:30:08

Janiffer
Replies: 5

how do u  find the taylor polynomial of degree 9 of f(x)= e^x about x=0?

#20 Help Me ! » onto and one to one » 2008-04-26 02:28:55

Janiffer
Replies: 9

hey... Suppose a linear transformation T is defined by a 4x3 matrix, can T be onto?

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