Multi family :calculating purchase cost

[Raj Parwani]

so lets say the NOI is 100K . if you want to know what price to offer , would you use 6% cap rate or 9-10% cap rate. With 6% cap rate you would offer 100K/6% = $1.67M. but with cap rate at 10% : 100K/10% = $1M. How do you know which cap rate to apply? what is the normal cap rate used in 5 plex? Do we use NOI in the 4 plex to calculate value ?

Thanks 

raj