# Need some help with some linear algerbra

• May 18th 2008, 06:07 AM
sterps
Need some help with some linear algerbra
Im having trouble doing questions 1 and 4 on the following sheet, would someone please help get started, thanks!
• May 19th 2008, 05:09 AM
CaptainBlack
Quote:

Originally Posted by sterps
Im having trouble doing questions 1 and 4 on the following sheet, would someone please help get started, thanks!

1. consider the column vector ${\bold{p}}=[p_t, p_b]'$ the first element of which is the probability that the student travelled by train yesterday, and the second the probability that they travelled by bus yesterday. Then from the statement of the problem we know that:

$
{\bold{A}}\left[ \begin{array}{c} 1 \\ 0 \end{array} \right] = \left[ \begin{array}{c} 1/3 \\ 2/3 \end{array} \right]
$

So the first column of ${\bold{A}}$ is $[1/3, 2/3]'$.

Similarly by considering its action on $[0,1]'$ we can conclude that the second column of ${\bold{A}}$ is $[2/5, 3/5]'$.

So:

$
{\bold{A}} = \left[ \begin{array}{cc} 1/3 & 2/5 \\ 2/3 & 3/5 \end{array} \right]
$

That's you started.

RonL