Info record price

Can anybody clarify how info-record price gets updated?

What will be the price as per info-record in the following cases

1) Material is created newly and vendor is also created newly on 01-01-2009. There is no info-record created with ME11

1st po price PO Dated 01-01-2009 - 1,000 usd

2nd PO price PO dated 02-01-2009 - 1,200 usd

3rd PO price PO dated 03-03-2009 - 1,300 usd

4th contract (qty) on same vendor dated 04-04-2009 usd

map as on 01-01-2009 - 800 usd

2) Info record is created for material-vendor combination on 01-01-2009 with price as 700 usd

1st po price PO Dated 01-01-2009 - 1,000 usd

2nd PO price PO dated 02-01-2009 - 1,200 usd

3rd PO price PO dated 03-03-2009 - 1,300 usd

4th contract (qty) on same vendor dated 04-04-2009 usd

map as on 01-01-2009 - 800 usd