how to scroll to view

I use listbox in a view:

<ScrollViewer x:Name="scroller" >
    <ListBox x:Name="lstRemarks" ItemsSource="{Binding Remarks}" ItemTemplate="{StaticResource RemarkListItem}" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" SelectedIndex="{Binding RemarkSelectedIndex, FallbackValue=-1, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ItemContainerStyle="{StaticResource ListBoxItemStyleTest1}" />
</ScrollViewer>

I am trying to synchronize scroll and the selected item,
when an item is selected the scrollviewr should scroll to the selected item so the user can see the item

I am using silverlight 5.