Question 1064779
A baby shoe box contains 7 shoes, two left-foot shoes 
and five right-foot shoes. If two shoes are randomly 
selected from the box without replacement, what is the 
probability that there will be one right-foot shoe and 
one left-foot shoe selected?
<pre>
Two ways to do it:

First way:

{{{matrix(1,9,

(matrix(8,1,Probability,that,first,shoe,is,a, right-foot,shoe)),
""*"",
(matrix(9,1,Probability,that,second,shoe,is,then,a, left-foot,shoe)),
"",
""+"",
"",
(matrix(8,1,Probability,that,first,shoe,is,a, left-foot,shoe)),
""*"",
(matrix(9,1,Probability,that,second,shoe,is,then,a, right-foot,shoe)))}}}

{{{(5/7)(2/6)+(2/7)(5/6)}}}{{{""=""}}}{{{10/42+10/42}}}{{{""=""}}}{{{20/42}}}{{{""=""}}}{{{10/21}}}

-------------------------------

Second way:

{{{matrix(1,4,Number,of,successful,pairs)/matrix(1,4,Number,of,possible,pairs)}}}{{{""=""}}}{{{(5C1*2C1)/(7C2)}}}{{{""=""}}}{{{(5*2)/21}}}{{{""=""}}}{{{10/21}}}

Edwin</pre>